Figured out I can just remove the editable = false flag from the Closed step of the classic workflow instead, so I did that. Seems to have worked - as far as I can tell there wasn't anything where we very specifically didn't want people to be able to edit closed tickets, so. If we don't want this for all the stuff in the classic workflow, I can always add a new workflow for INST instead, but that's slightly more effort (like, five minutes).

Took a quick look, and I think that's because INST (like AREQ, LB and a few others) uses the "classic" workflow scheme, while PICARD, MBS, etc use the (more powerful, it seems) MusicBrainz workflow. Changing INST and the others to the MB workflow probably will fix this, but also add stuff like "in beta testing" and "in development branch" to them. I guess we could just do that and ignore those extra steps, up to @Freso