given that comment mentions "fix coastline around adriatic sea, revert boundary imports that broke it" without commenting on documentation of import I expect that breaking coastline was cause

Not in DWG so I cannot say what would be the action if lack of docs was sole issues but I expect that there would be first request to explain and link documentation if nay

> Here is the wiki page: https://wiki.openstreetmap.org/wiki/Croatia/Import_administrative_borders

oh, great! Can you add it in changeset comments of previous edits or at least on https://www.openstreetmap.org/user/Import%20DGU%20borders user page? And link it in future changeset tags (in edit comment or in extra tags, JOSM can easily do this)