Wouldn't opening the artist page and checking for redirections be sufficient? It's also possible to take the first search result returned by LyricWiki, but it can be risky (IMO no lyrics are better than wrong lyrics). Unfortunately, those options require downloading 2 pages instead of 1. Assuming that the number of hits is significantly greater than the number of misses (including lyrics that really do not exist, not just those with mismatching artist name), the number of pages can be reduced to 1 most of the time by using the 2-page routine only as a fallback (but the worst-case outcome is 3 pages)
QString artist; // is our current, read from the file artist = settings.getValue("artistOverrides/artistName", artist) // do something with it