That thread was for character suggestions, there was a different one for the release, which I think makes more sense to link here:
Anyway, maps and portraits don’t really take that much space, a portrait is I think a bit over 4000 bytes, so 256 portraits would take about one MB, one of 32 you have to play with in total.
For maps it depends on the size of the map, but they really don’t take much data at all either, even if you make 256 maps it’s not going to take much space.
Oh, and many flashcarts have issues saving on the GBA FE games because of the type of memory those flashcarts use, sine FE saves constantly (for the resume function) the flashcart can’t keep up and the data gets corrupted. If you want your game to be compatible with all flashcarts you need to disable the suspend data updating automatically.