Yes, this is a total buffer solution as the complementary acid for the Carbonate buffering system is Carbonic acid, H2CO3. This is formed automatically in the water when CO2 from the air dissolves in the water, and when CO2 from the fish, shrimp etc. is expressed into the water. Adding a Carbonate salt, whether Calcium Carbonate, Magnesium Carbonate or Sodium Bicarbonate will automatically balance with the Carbonic acid that is in all aquarium water to form a buffered system. You can vary the pH level a little by which Carbonate salt you use, Calcium Carbonate produces a pH of 8.4, once this is reached in the water putting in more Calcium Carbonate won't raise the pH of the water any further. Sodium Bicarbonate will produce a pH of 8.8 before adding more doesn't change the pH. Having the complementary acid always present in the system is why so many don't realize that it takes both the acid of the anion and a salt of the anion to form a buffering system, because they just add a salt of the carbonate anion in the form of limestone without needing to add the complementary acid to "buffer" their water.
Other anions can form buffering systems at different PH levels, the products promising to buffer your water at a pH of 7 use the phosphate anion (phosphoric acid and usually ammonium phosphate as it dissolves easily), which has the problem of causing algae blooms by unbalancing the plant to light to fertilizers levels. Using the Citrate anion (citric acid and trisodium citrate) will buffer water to a pH of 6, but causes problems in aquariums as the Citrate anion is part of the Krebs cycle which all organisms that use oxygen to produce energy in the form of ATP molecules; like fish, shrimp, snails, the nitrogen cycle bacteria etc. use to live. Living in water with lots of citrate anions in it doing the pH buffering messes up the Krebs cycle in the organisms cells and causes things to die. Small fish, shrimp and snails can survive for days to weeks, large fish for months, being large organisms with some capability of storing ATP to use later, but single cell bacteria doesn't and dies quickly stopping the nitrogen cycle that depends on them.