Unforuntately, we never did get that part of the mapping done on either classic or threads. The main one that was concentrated on during the initial creation was just getting all of the topics to redirect properly.
no biggie, think about it, the redirectors are for search engines, and their last crawl before your migration has all the data it will ever have for your forum...
So why does it need to crawl forums, it has your posts, and thats all that really matters... a cat/forum redirector would simply forward to a new location, which would be crawled the second that google (or any other SE) sees your new forum index (as they're the first links it sees at the new location)
