The ASM routine(s):
As you said, when it checks the amount of map names, if that amount doesn't match up to what's in the routine/routines, the game will crash, right? Well, what if you change the amount of names that ASM routine(s) looks for? That way, you can expand the table, and the routine(s) will match it properly. I wouldn't know where to look, but do you think that ASM routine/ those ASM routines could be modified?
EXAMPLE (note, I'm making an example, NOT writing out an entire ASM routine, as I don't know ASM)
Amount to look for: 9F:Map Name 128
Change the routine to do this:
Amount to look for: AA: Map Name 138.