I can answer some of that. Only nonsense, cutesy sounds are left as is, if appropriate. Sounds like Kyah! Fuwaaa! Un... etc. The rest are, well at least I try to be as close as possible to the original though some creative license are used on some generic characters to give them flavour. It's turning into a great exercise for my creative English writing since I have lost a lot of practice with it, considering I write reports most of the time on the job. It's a great break and it's great practice for my Japanese reading comprehension, which I still struggle with.
There is a central 'Editor', if you would call it, that will review the translations given to he/she/it and will apply consistency to the translation, make sure that every name and personality portrayed is consistent since we're just translating blocks of text without context.