Hey Jagster
Did you have a look at this?
I’d look twice before doing such a task though (on a test server, or have a backup ready) because some of these tasks didn’t populate some tags table when I used it: Bulk tagged topics, then moved topics into another category, but the category tag selector doesn't show tags - #2 by Canapin
I don’t know if it’s repaired, I didn’t try again since my migration. But I should!