In general, moving topics between remote categories is disallowed because it's misrepresentation. You're limited to moving uncategorized topics to a local cid, topics between local cids (of course), and cross-posting topics to local categories.
There are some gaps in federation, as @informapirata states. I've been actively working toward finding and closing those gaps.
@informapirata @sj_zero@lotide.fbxl.net @kichae@wanderingadventure.party