This is what I managed to scrape together:
It doesn't matter if it's a modification or not, what matters is the type of property. I do not believe regeneration per hit is increased by aspect lore, but it may well be.
Each Aspect Lore page on the WIki lists any additional effects that get increased in lieu of damage.
Did you rule out the possibility that Regeneration per Hit on spells is just a flat number, like the version on weapon hits?
There are only two types of bonuses that get used for RpH:
type = "BONUS_ENERGYLEECH_WHIT", -- this used for the the RpH item modifier, Alchemy trophies, and also on Magic Coup.
type = "BONUS_ENERGYLEECH_ONCE", -- this is used on Callous Execution, Dislodged Spirit, & Jolting Touch.
Often when a bonus is percentage-based on the scripts it will have the _REL suffix, for example "BONUS_LIFELEECH" vs "BONUS_LIFELEECH_REL".
Just something to consider.