Swords are just hogs for nutrients, they don’t care where it comes from. People mistake large root systems for root/ heavy root feeders. The larger root systems are for anchoring mostly. Usually from seasonal flood areas or faster than normal flowing rivers and such.
Here’s a good little blog post
https://www.2hraquarist.com/blogs/fertilize-planted-tank/root-or-water-dosing?_pos=2&_psq=root feeder&_ss=e&_v=1.0
You should be concerned with 0 nitrates. Plants need N, P and K along with micro elements. If any of these bottoms out, the plant begins dying.
Also, Swords do not need root tabs, water column dosing is all that’s needed.
1 is all you would need and has enough par to grow any plant available to us. CO2 would be the only limiting factor.
My PC monitors are trash for editing and sorry the the pictures are so dark. But I assure you, my tank looks a fruit market at high noon on a clear blue sky day.
The weak point on the WA is they are fan cooled and is a failure point of the light.
Never used or seen Ledstar, but have WeakAqua P's. They look to be both similar in spectrum and WA can pump quite a bit of par. WA is more popular and is catching on fast in the upper end of planted tanks. Here's my AGA shot under WA and a few recent shots with different exposures.
I agree with @gjcarew, this sounds like a toxin was introduced. I know here, in the winter, they increase chlorine dosing. I can smell it from the faucet and it irritates my eyes in the shower.