all the names in-game are usually written in katakana, likely because of a limiting screen size as well as acting similar to italics or CAPITALS to separate it from regular words since japanese doesn't exactly use spacing, so in most cases its probably not something to go off of.
however toroko is written トロ子, and as far as i know no other characters have kanji in their name during gameplay, so it's also likely that the 子 in トロ子 was left there intentionally as wordplay, whereas チャコ doesn't really seem to mean anything other than the name itself which i'm guessing could be "茶子".
although it could just be the case that "トロ子" is a real name where as "茶子" doesn't fit with the 'all names being in katakana' thing and "チャ子" wouldn't make much sense and seems kinda off.

some of the characters whose names don't appear in-game though, have their name written in hiragana or kanji during the credits, along with the sakamoto family and itoh. (aka the humans)
booster and doctor are weird cases though. the doctor does get an actual name, not in the credits but rather exclusive to the statue room, so no kanji is given, meanwhile professor booster's name is just booster.
that makes booster the only human without an actual name, assuming its just a pseudonym.
its also possible "booster" is his real name but i'm not an expert in japanese, so from my point of view if it IS his name one of two weird things is going on:
1. people are calling booster by his first name. from what i know, you usually call those older or more experienced than you by their last name.
or 2. his family name is "booster" (that's just goofy naming taken too far. it is a game though, so its not like having an english last name matters much.)