I don't think this has to be a strict either-or case. The stylized version of the title seems to be common too and IMDb suggests it as an alternative title. So none is exactly "wrong" or "correct". We don't necessarily have to make a strict decision there, let alone are able to do that. Other examples similar to this would be Fant4stic or Se7en.
Yes, in case of tags we need to choose one and it seems the tag uses the more conventional version that IMDb also uses as primary title, similar to the other two examples mentioned above. But in the question bodies there might be more leeway for stylization like that, which is why I rejected your specific edits as that was the only thing they changed.
However, what might be a good idea would be a tag synonym for the-vvitch, similar to the one for fant4stic.
Regarding searchability and pronounceability, that's part of what tags are for afterall. And once both titles exist as tag synonyms, they should be used for searching anyway, especially since often people don't even mention the title in their question body. Yes, they should for a self-contained question, but you can't really rely on that.
Wait, it seems I misread and IMDb actually uses the more unconventional version as the primary title. In that case maybe that could be the primary tag name. But anyway, a synonym makes sense in any case, the master and synonym can easily be swapped later on. I still think there's no problem with allowing both spellings in the question text itself and if we swap the tags, suggesting edits for "VVitch" on the other 6 questions might not be the best idea either.