According to the official lodestone-database, the rings are still obtainable from a chest at 11,5/9,9 (thats the chest on the hill) - however, on the run I just did to check it out, I didnt get a ring out of that chest... but out of the chest at 12,0/8,3 (thats the one thats a bit "off the path" before the second boss). Both chests required goblins to be saved before.

So it seems those rings are still obtainable from the dungeon, just not from the chest they used to be in or from the chest the lodestone claims...