OutBout

A seasoned tank will help, but plants will need to go through a transition period when adapting to a new environment. This is seen in emersed versus submerged, CO2 versus non-CO2, inert versus nutrient-rich substrate growing conditions. Bucephalandra is rather forgiving, but is a slow grower and can take forever to get new growth if CO2 isn't added.

Do you know if your plant started off in emersed form? Personally, I've tried Alternifolia reineckii a few times years ago with little success. The plants were emersed grown, I had poor lighting, and nutrients seemed to be an issue as well. Everything melted away eventually. Last spring I randomly decided to pick up an AR tissue culture and grow it out in my emersed cryptocoryne tote. The plants did well enough to then transfer them outside to a shallow pond once the temperature allowed it. To my surprise the AR really took off, easily competing with its Hygrophila polysperma 'Sunset' pond neighbor. The pond contained a nutrient-rich substrate made up of only miracle-gro gold, filled up with soft water, and exposed to full sun for at least 8 hours a day with the water temperature averaging at 70-72. At the end of summer I moved half of the AR plants to a 75 gallon tank I was setting up. I planned for this setup to have soil capped with crushed granite and Barrina grow lights. I expected sustained growth size-wise from the AR, but it actually increased in size and color intensified. This was all without supplemental water column CO2, though adding it would definitely accelerate the growth rate. Long story short, from my year-long experience, AR is a heavy root feeder and thrives with good lighting. Here's how the tank looks currently.

The Sewellia hillstream loaches are omnivorous grazers, not obligate algae eaters, and will be eating the stuff (biofilm, aufwuchs, infusoria) that's living on top of the algae. In my experience, if given the choice, reticulated hillstream loaches will flock to any sinking food instead of focusing on the algae areas. I would say that nerite snails are better at algae control, as I've never seen any go for prepared food if there's enough algae to satisfy their hunger.

Looks good! Using individual planter containers should work out too. Did you place a light for the tote? If not you could place it near ambient daylight or another tank's. The nice advantage with a dedicated light is that the small sealed container will get some residual heat. Another idea is placing your container on top of a refrigerator or freezer. The tops of these appliances radiate heat due to the cooling processes and can keep a tote warm! In terms of misting, I usually do it on the ceiling of the lid before closing just to get humidity throughout. The water will drop down and evaporate into the container air when combined with heat. Furthermore you can also get some sphangum moss (I do the long strand type that's used in terrariums) and soak it really well before putting it on the bottom of the tote around the planters. This will also help with maintaining an even humidity. Here's a picture of one of my totes. I didn't use aquasoil in this one, just equal parts of peat moss, safe-t-sorb, and earthworm castings. So far it's grown most cryptocoryne and other miscellaneous plants!

I usually use a clear storage container called Ezy Storage IP67. There's various sizes and it has a rubber seal which allows for moisture to stay in. There's similar products around, but these totes are quite sturdy and fully clear! Using an empty aquarium with a clear lid will have similar results as well. For high humidity, misting is one way to go and also keeping the substrate moist. Just be sure to have a light and possibly some heating, and be wary of mold developing. One of my experiments I planted tissue cultures of C. purpurea and C. spiralis 'Red' in glass jars with latching lids containing Fluval stratum. Filled the jars with water up to the soil level and placed them in the kitchen that's very low light, and ambient temperature of the house (64-70F). To my surprise the crypts grew, although slowly, and eventually were quite bushy by one-year's time. If you're interested and have the ability, see if you can apply the the suggestion from @Cory about aquasoil. Take the same crypt and plant it in various substrates to see how they perform. Later on maybe change another parameter and keep a record, but just don't change too many things at once as then you won't know what affects what.

Good call on keeping a personal database. In terms of accurate information, I'm not sure that a business that wants your money is the most forthcoming about compatibility. Of course there are the more ethical shops out there, but being in business means they want to sell you products and more of them. For instance, crypts as a group seem to be lumped together as "beginner" plants, and while it's true to a degree, there is still quite a variety that includes many finicky species. Regardless of this point, have you looked into the website 'The Crypt Pages'? It's a little outdated and anecdotal at times, but the information (however limited) seems mostly in line with how my various cryptocoryne have performed. As for tissue cultures, 90% of mine perished when I placed them directly into an aquarium. My strategy is to first plant tissue cultures in a high humidity tote that has lights and heat. This allows for the lowly plants to slowly adjust to an environment outside of a a super-rich agar, while staying emersed. The high humidity also helps when if I decide to transfer them to a running aquarium, as I've noticed less leaf loss. Alternatively, crypts that I've kept in relatively medium humidity (60-65%) melted within 24 hours upon being placed in an aquarium.

Plenty of good suggestions here! Consistency and stability is key with cryptocoryne, but also be aware some prefer soft water (blackwater) or hard water (limestone deposits). My last aquarium that was dominated with crypts was loaded with mopani wood which created nice blackwater conditions. I hardly changed water in this tank, and the parameters were: pH 6.0-6.4, Kh 1-2, Gh 4-5. I tried out various types of crypts and predictably the hard water ones (C. hudoroi, C. aponogetifolia) croaked. However, other crypts such as the C. nurii group, C. affinis, C. jacobsonii all thrived due to their soft water preference. Also consider that cryptocoryne will have a transitional period where they will lose leaves, and the rosette with roots will stick around. The triggers for crypt melt are numerous, including: emersed growth to submerged (and vice-versa), temperature, humidity, nutrient availability (tissue culture media to inert substrate), water composition, health of plants (sterile tissue culture plants never being exposed to various pathogens). A suggestion to help with this transition is to either cut the leaves off at the time of placing them in the water/planting or cut them when you start noticing malnutritional signs. This will reduce energy expenditure for the plant as it'll try to repair and preserve damaged leaves, and new leaves should follow. Furthermore, cryptocoryne can be exceptionally slow growers. Adding nutrients directly to roots and having access to higher concentration of CO2 can create an environment for a smoother transition. What species of crypts have you tried out? I've found that C. undulata and C. spiralis to be quite hardy to many parameters. Hope this helps!

Cool idea with having carnivorous bog plants at the pond surface. Do these plants care if their roots are constantly wet or do they need a dry period?

Welcome! I've taken a similar journey where I fell out of aquarium keeping years ago. Good to have you back.

Without a clearer picture of the leaves I'm going to guess Anubias nana.

Oh looks nice, might have to get one!

Fun idea! Swiss chocolate sounds awesome too!

Egg survival is luck of the draw inside a community tank. But this also means your cories are feeling happy and well fed, so congrats!

A type of algae. No real concern. How long has your aquarium been running? New aquariums tend to take time to reach a point where plant growth out competes algae.

Good advice. Mopani doesn't really stop leaching tannins, just slows down over time. I have noticed that mopani that's only composed of the dark brown wood will leach much less from the start. Personally I've never boiled mopani and have always enjoyed the black water, though the pH can drop a bit.