I admire your dedication, but be warned... by the time the plants star failing the soggy soil will be growing bacteria and that rotten egg smell seems to never go all the way away lol.

Is the island flush against the bottom of the tank? How deep is the spray foam at the bottom of the pot in question?

Hmm then you have gravity working against you. If you don't have a drainage layer and put a tube in it to your water feature for drainage you will risk having water flow from the water feature into the pot. Unless your pot is elevated above the water line to begin with I don't see the tube idea working out for you.

I hope you are able to solve this and salvage your baby, but sometimes you can scrap a setup and replicate it with some minor flaws fixed and end up with something you love even more