Is there a canonical source for this information? I know ヴワル魔法図書館 is the title of EoSD's stage four BGM, but I wasn't aware it was unequivocally stated by ZUN anywhere that Voile is the name of the library. (Personally I always figured he meant for it to be 'Voila' in the song title.)
Official EoSD music comment stated: ヴワルというのは固有名詞なんで余り意味ありません。フランス語かなんかで、なんか意味があります(笑)
Translation: Voile is just a proper noun and doesn't have much of a meaning. Although it does have a meaning in French or something (lol).
ヴワル/Voile was intended as a noun and not voilà (the latter's romanization should be ヴォイラ anyway). That said, it's true that Voile isn't considered the library's canon name. No characters nor narrative lines in official works had refered to the library as 'Voile'. The official manga's error correction henmere pointed out is an added evidence that ZUN doesn't want to make Voile the official name.
Personally, I have no investment in voile as a tag. I just stumbled on it while tagging a series of images, and thought it needed a link to library if preserved. I have no objection to eliminating the tag and merging.