Just wanted to add that cut-and-paste is pretty freeform on Bugzilla. It wasn't possible to get all the cases right, and handling some would have messed up others IIRC. So I picked some heuristics that mostly worked on my test migrations of GJS. Even so, I had to edit some bugs and comments to add markdown formatting, so I expect that maintainers will need to do that in some cases for GTK as well.
I'd be happy to review any updates to the migration tool that improve its ability to guess whether a particular paragraph should be enclosed in triple-backticks or not.