Thanks for the reports.
One more thing I noticed we should confirm:
Casual difficulty lists a penalty to loot in the tooltip (cant remember if it was -1 or -2), but it isnt clear if its in addition to the standard quest level reduction or not..
So need a report of a +2 tome in lvl15 casual quest, or +3 in lvl23. (or equivalent with bonuses.)
Also updated to note that chest blessing is only +1 loot, per developer confirmation.