Issue: URL encoding (or lack thereof) wreaking havoc

Special characters like this are automatically stripped from the URL. & is changed to "and". If you're having trouble with these, it's likely you had multiple articles in your source wiki that were redirects with slightly different names, but these all have the same URL in VaultWiki because of the way the & character is encoded.

Basically, you don't need as many redirects as before. Go ahead and delete the extras. To do this without access to the affected articles' edit tabs, go to VaultWiki > Wiki URL Manager. You'll see a list of pages with URL conflicts.

Also, vBulletin doesn't support HTML in titles, so don't use &, just use &

Because you had multiple articles taking over each other's URLs during the import, you may need to rebuild URLs as you remove the excess, if you don't use the admin page mentioned above. VaultWiki doesn't look for other pages using the same URLs when you delete something any normal way, the URL for it is just deleted. To rebuild URLs, VaultWiki > Namespace Manager. For the affected namespace, click Rebuild.