Basically, the problem I was seeing is:
- We move the LQT page (e.g. Talk:Foo) out of the way to "Talk:Foo/LQT Archive1".
- We tell LQT to process the move (
it does a limited amount of the processing immediately before we tell it, but we need it to do all immediately; see T95633: LQT conversion may fail for LQT talk pages with more than 500 threads).
- We immediately continue and start copying data from LQT via its API (for this path we use a FauxRequest API call since it's the same wiki), but LQT doesn't see the content at Talk:Foo/LQT Archive 1.