Hi,
I would use a feature of spellchecking filenames with a 3rd party spellchecker (MS Office/ OfficeLibre/ Hunspell/ whatever).
This feature should of course support editing of filenames during spellcheck, similarly to using the spellchecker in a text editor.
That's an interesting idea, although I suspect a lot of UI work to add, and I think a lot of everyday filenames would be flagged as spelling errors (which might be more annoying/confusing than helpful) so I don't know how well it would work in reality. Might be worth looking into some more, though, certainly.