I've run into the savegame rollback bug as well, but with a few twists. I opened up DTD to find that my kingdom had reverted to an older state, with very few unlocks and not much gold. The thing is, the data from specific runs was still intact, so after I completed a single dungeon, I got bombarded with new quest triggers, opening up new dungeons, completing quests and challenges, etc. After a few cycles of this, I had retriggered most of the missing content, but with some expections:
Gods were still locked. Their special "hazing rite dungeons" still appear, so at least it's recoverable. Some deal with races.
The Tinker was missing. Unfortunately, his trigger didn't reset, and now he never appears, ever. This means that the Alchemist and the Tinker are both lost forever.