Hmm... so there's two solutions, here. It all really depends on how you want to do this...
Solution 1: Use a program like photoshop or aseprite, and combine all the sprites into a sprite sheet. Doing it by hand would be a pain, and I remember from my pixel art days that there are scripts out there to do this. If you're searching by index anyway, then it's just a matter of... <q=cardsprites,x>!
Solution 2: Use a script that generates STMQuadData files out of a sprite array. If you want to go with this, I can write the script for you as part of this support! You'd end up with one STMQuadData file for each sprite, but the names could be auto-generated from the sprite's name, so you could have... <q=symbol> <q=othersymbol> etc. I will say, this method is less rendering-efficient, since every unique texture means a unique material.
Either way, using a program to set up 100s of these is what I think should be used! No one should have to define 100+ sprites by hand.