I found one workaround that’s not halfway bad - as I’m improving my parser which cleans up the import file from Vanilla, I tend to focus on mistakes that occur i specific posts.
So as I improve my parser, I can stop the parser in the debugger (I’m using Xojo, for what it’s worth) and get the Raw Text.
Then, in the live discourse forum, I can simply add a new post, paste the text in, and see how it looks.
This allows me to do a test/debug/change cycle of a few seconds, rather than an hour or so.
My new plan: after I’m happy with my parser cleanup, then I’ll nuke the Discourse and re-install from scratch.