Hello. I also have suffered from the character gender glitch. I had the male, dark-skinned character and it turned to Marianette after the library event... What should I do? I guess I'll keep progressing in the game until a new patch is posted...
EDIT
I found a short term solution on a youtube comment, but it didn't work for me. Maybe it will for you.
"Pretty much what happens is that the game changes to the default avatar (the boy with green hair and the hat). Easiest way to fix it is to switch the names of all the sprite files so the character you had been using becomes the default. So you would go into the GRAPHICS folder then into CHARACTERS. Then you would just switch the names of the files relevant to the default character which you turned into, and the character you want to be (the black guy). For example, if the name for one of the sprites sheets of default character (the guy you turned into) is named "boy_bike00" and the sprite sheet of the black guy is "boy_bike02", you would just switch the names so the latter is now named "boy_bike00" and vice versa. Another example is if one sprite sheet of the default is "tr_char00" and your former sprite is named "trchar02". You just switch the names, simple. You have to make sure you do this with every sprite sheet for every action though (such as biking, surfing, running) otherwise you'll switch between sprites everytime you do one of these actions. Most of the sprite sheets you'll have to rename in the CHARACTERS folder will start with either "boy" or "tr_char" but dont miss any of them. Also, during the final battle the glitch will temporarily "fix" itself so if you do this before the final battle, you'll once again turn into the (original) default sprite (the green haired boy with the hat). But after the battle the sprites should change back again."
Game.rxdata