I like your app not a game, no ads (good for you.)
You may want to try
Braille type 1,
Braille type 2,
Braille type 3
tabs they are also called define or undefined or something like that.
Flash cards: cards print out on a letter size paper can place 12 or so on one sheet and make it a two page think with instructions on placing it back into printer to print it on the backside of card so that you have the answer that way.
Braille keyboard layout like the real ones out there for the blind may help. To learn the 123,456 placement on the app.
The spell area the “y”is not a “v”. I place the dots right on the other parts of the app but the spell says “v” for “y”, these may have problems with other letters, spell check your app please.
There are external keyboards out there for the blind your app can Bluetooth with them can help.
More later.
Thanks for the wonderful app.