I have an Edge as well, I made the same lighting upgrades that you just mentioned. In my opinion you will definitely need more light to get the baby tears to carpet or even thrive. I have had Dwarf Hair Grass in my Edge, I planted in tiny little plugs all over the place, I found that the lighting was not enough for it to thrive either. It grew very very slowly and in the 2-3 months that I had it, it never spread, just the little plugs reached for the light.
Flourish should be fine for your snail. I have never had a snail that I wanted to keep alive, but I have used Flourish with shrimp galore, and never had an issue.
As far as getting more light into your Edge, I would recommend that you check out "The Official Edge Thread" https://www.plantedtank.net/forums/pl...ge-thread.html
, there is a wealth of info there, as well as documentation of other peoples mods, of which there are a lot. I have just resigned to using my edge for what its good at, low light, low maintenance.