If it makes you feel any better, what you've done happens all the time! Acid-buffering substrate with a CACO3 stone that "fight" one another, and conflicting information between the two genera of shrimp can cause a lot of confusion. But where you are right now should be a perfect environment for crystals, bees, and such. Aqua soil, remineralized RO water (GH+ only, not the KH and GH product) and you should be all set for most Caridina.
If buying shrimp online, just be sure that they are "home bred" and not imports. Survival rate is typically much higher this way. I prefer to buy from other hobbyists whenever possible.
If you really want cherries (Neocaridina) they will live on Aqua Soil but the water will always be softer and more acidic than ideal. But cherries are tough creatures and people keep them in tanks set up for Caridina all the time with success. As for how long the substrate buffers, that is determined by how much "work" it has to do. If using soft water and no lime based stones in the aquarium, it is said go for many years. You don't want to speed that up in my opinion, kind of defeats the purpose of buying buffering soil.
Hah! LOL, how did I know.
If I was going to put a bet on one or the other, it would be the rocks from Phillip Island ... from the beach.
How to test? do the vinegar test.
Take out a bit of gravel, and a small stone. drop some vinegar on them to see if you get a reaction.
Alternate test is to put them in a cup of water. Test the water GH and KH before adding, then test again after a few hours to see if KH and GH have increased.
ahh shoot. gravel was washed about 20 times thru, and rocks were boiled. gravel was sold as aquarium safe gravel, but the rocks were from phillip island, along the beach... how could i just test 1 or 2 to see if that's why? (they're all the same type, but i have a few big ones that r heavy and a bunch of small ones that i can test with)