The most common problem I have with getting map chests are the warriors of the damned. Theyre way too strong. Im lvl 41 with full plate armor, a heavy mace, drinking grog before the fights, and Im getting destroyed by a single lvl 15 warrior. By the time I manage to kill them by luck without dying, the whole group respawns again, and if the first warrior isnt already dead, then another spawns with the new group so Im fighting off 2 warriors now. Another time I had 4 warriors spawn and by that time I just had to abandon that chest.
I think Warriors of the Damned should at least spawn last AFTER youve killed every other lesser undead, so the Warrior at the end would be a 1v1 mini boss to defeat to then dig up the chest. Having them spawn at the same time as all the others is just overkill on a player.