Ascalon Explorer - Vexa's Lab
No. Probably because they don’t want achievements to go backwards(aside from when it is caused by a bug). World Completion status can go backwards but that doesn’t affect the achievements and it can cause people to go back to old areas which is something they DO want.
But the Shiverpeaks explorer got increased. I think it was at 172 at release and people that got the 172 areas discovered and have not played until now would have 172/175 with 3 new areas(I think 1 jumping puzzle 1 mini dungeon and the Cragstead area).