Been a while, but I finally got around to messing with this code again, and I figured out how to make it work without taking up a ton of memory.
Basically, I first made the "easy to reference" alphabet into global variables with placeholder characters (basically just a bunch of "X"s). Then inside the setup() function, I made the multidimensional array with all 3 languages (3 x 36 x 8 array), making that a local variable instead. Kept the same method of having the user choose the alphabet inside the setup() loop. Then, depending on their choice, a for() loop (still inside the setup() loop) goes through all 8 bytes of each global alphabet character and replaces it with the corresponding letter of the alphabet referenced from the multidimensional array. So basically:
for (int counter = 0; counter <= 7; counter++){
ma[counter] = {languages[selectedLanguage][0][counter]};
mb[counter] = {languages[selectedLanguage][1][counter]};
mc[counter] = {languages[selectedLanguage][2][counter]};
md[counter] = {languages[selectedLanguage][3][counter]};
...
}
That way, I'm not taking up a ton of unnecessary global space because the multidimensional array with all three languages is contained locally within the setup() loop. Seems to work. Thanks to everyone for your help and input!