Painter-kun and Cripple-tan are fan-made names in the English-speaking community. Their real names are Kamen and Aojiru/Aoshiru respectively.
Most of the characters do have official names, but the trend of giving names to minor characters from Yume Nikki has passed down to this game too. The Japanese community have acknowledged that we have different names for some characters eg. Elvis Masada, so it isn't a major issue.
I am wondering whether we should change the main names of the character articles to their Japanese names and just leave the fan-made names as redirect links.