Tethmos High Priest has the heroic ability:
Whenever you cast a spell that targets Tethmos, return target creature card with converted mana cost 2 or less from graveyard to battlefield.
The last sentence of 601.2c is:
Any abilities that trigger when those players, objects, and/or zones become the target of a spell trigger at this point; they'll wait to be put on the stack until the spell has finished being cast.
My interpretation of 601.2c is that Divine favor starts one stack, and when that stack gets resolved, another stack is processed that starts with the Tethmos heroic ability being triggered.
So in this specific case where only one instant is cast (negate), Divine Favor gets negated and has no effect. However, the heroic ability does get triggered.
Is this interpretation correct?
Is it the case in general that heroic abilities do trigger even when the enchantment is countered?