@DrChiper: I dont see much need for auto-renaming files, since the file browser displays the files in spine order anyway, regardless of their names. I do plan on creating a tool to bulk rename all file, putting them into a "standard" file structure.
The treatment of character ranges depends on the case sensitive setting. This is particularly useful with unicode ranges, since the regex engine supports full unicode case folding. In any case, this is not something in calibre's control, it comes from the regex engine
https://pypi.python.org/pypi/regex
@samy2: Is that for just one particular file/book or all of them?