Anyway your reasoning for the evards is off, also because the reason you used is not valid anymore in 3.5 where the tentacles behaves exactly the same.
Let's stay in 3.0 land for the time being. Remember the 3.0 description for empowerment.
Empower Spell [Metamagic]
Benefit: All variable, numeric effects of an empowered spell are increased by one-half. An empowered spell deals half again as much damage as normal, cures half again as many hit points, affects half again as many targets, etc., as appropriate. Saving throws and opposed rolls (such as the one the character makes when the character casts dispel magic) are not affected. Spells without random variables are not affected. An empowered spell uses up a spell slot two levels higher than the spell’s actual level.
I have added bolding to the curative words which are in parallel to that "half and again as much damage as normal", implying "half again as many hit points (as normal)". What spells would actually cure 50% more hit points than normal?
Cure light wounds (Note the wording is very similar to the NWN wording you brought up).
When laying the character's hand upon a living creature, the character channels positive energy that cures 1d8 points of damage +1 point per caster level (up to +5).
Cure moderate wounds
Cure serious wounds
Cure critical wounds (all of these are phrased the same way as cure light wounds)
Healing circle
Positive energy spreads out in all directions from the point of origin, curing 1d8 points of damage +1 point per caster level (maximum +20) to nearby living allies.
Regenerate
The subject’s severed body members, broken bones, and ruined organs grow back. After the spell is cast, the physical regeneration is complete in 1 round if the severed members are present and touching the creature. It takes 2d10 rounds otherwise. Regenerate also cures 1d8 points of damage +1 point per caster level (up to +20).
3.0 reasoning strongly asserts that the + 1 point per caster level is included with the die roll when multiplying by 1.5.