I haven't tried modding the game in depth yet.
I feel adding custom characters will be hard because DLC ones take almost all free slot (there is only one left by default, chara14).
It's not impossible but you would have to modify 007_global.js, plus other files where the limit of 14 characters is used (and possibly the character select menu too).
Honestly, this part of the game would almost need a rewrite to dynamically load as many characters as we wish.
There is also the issue of the kakeai files (for discussions), the more characters you have, the more files you need.
I know the author of the exstia character mod back in the day hasn't bothered to port it to this version, yet.
EDIT²: Actually, it goes to chara0 to chara14, so that's 15 characters. I bet the chara14 won't even work because the game expects 14 characters in so many places. I have a vague memory the exstia mode fixed this part too.
EDIT3: chara0 doesn't seem in use, maybe it could be used?
EDIT4: There are places where the game expect 15 characters. This is such a mess, holy cow.
EDIT5: It turns out you can go over more than two lines of characters but it's ugly.
Final Edit:
I got a mod working, it's in the TL patch folder.
It extends the character limit to 32.
I also did some tweaks to the character select screen to make it usable with so many characters.
And I did another change to make it easier to add or make custom characters:
kakeai files are NOT required with. When they are missing, it'll load basic sentences instead.
I can't guarantee it's bug free, considering the little time I spent on it, but it seems to be working fine.
I-lied-another-edit:
I fixed a mistake in the mod, thanks to the author of the old exstia character pack. He got it working again in record time.
I might share it later (probably in the same folder) once he gives me the greenlight (he is a friend of mine but he lacks an account here).
