For the race ability lists, you can repoint them and such to get the max number of entries on each race at the same time, there shouldn't be an issue there, but you still can't easily give humans more abilities.
This is because of how AP for mastering abilities is stored. Each unit has about 0x90 bytes to store their AP progress for each ability. There may be a few bytes free in there, I haven't tested it thoroughly, but, considering this starts at +0x40 in the unit data and +0xD0 holds the CT, at most we are looking at 0x90 bytes, with humans already having 0x8D abilities.
If you do use the 1bit abilities engine hack then you no longer have to worry about that, since AP is completely removed and (as the name implies) mastery is stored in a single bit, leaving a lot of bytes free even after raising the limit to ability 0xFF.
This is because of how AP for mastering abilities is stored. Each unit has about 0x90 bytes to store their AP progress for each ability. There may be a few bytes free in there, I haven't tested it thoroughly, but, considering this starts at +0x40 in the unit data and +0xD0 holds the CT, at most we are looking at 0x90 bytes, with humans already having 0x8D abilities.
If you do use the 1bit abilities engine hack then you no longer have to worry about that, since AP is completely removed and (as the name implies) mastery is stored in a single bit, leaving a lot of bytes free even after raising the limit to ability 0xFF.