I think the amano shrimp should be fine unless they are really small juvenile ones- amano shrimp are very good at hiding, the best way to lure them out is to get some catfish pelets or algae wafers for them to eat and drop them at the front of the tank .
Having seen the way my subadult balas (6"+) wolf down feeder shrimp up to 2" and beyond, I would not recommend keeping amano shrimp in a tank with balas long term.