That's cool!
I am not an expert at the other languages, but I am learning some now if you are expanding into Swahili or Hawaiian.
I would love to help out on the English side!
I have been both a technical writer on a number of time-sensitive projects (whitepapers, SOP, instruction, system design) and a developmental and line editor for fiction.
Questions I have for now
Do I need to be fluent in two of the languages listed?
Do you have a design document or a goal of "strict, absolute grammar rules" or more "here's how an English/Spanish/French speaker would say it" type of editing?