Potent magic, variant spells, and Adaptive mastery?

Potent magic in THRE page 31-32 rules that Potent spells are invented a specific Potency (capped by Magic Theory) using specific casting items. And top left column on p32 states that inventing a variant with only change on these casting items takes only one season.
How is this variant to be viewed regarding Spell Mastery? Is it a completely new spell?
Or could one conceivably view it similar to "here all spells of a different level" like you do with Adaptive Casting (HoH TL p99)?
It seems detrimental to the usefulness of Mastery to force a magus inventing new versions to have to start Mastery from scratch again. And unduly harsh. Potent magic and Mastery doesn't mix well it seems. Seems a shame.
A broader interpretation of Adaptive Casting could fix this. Or if the scope of Adaptive seems too broad then, eg concerning a Potent General spell then define a new mastery needed to use the mastery of spell variants.
Better yet if spell variants just used same mastery as the original. But that seems too good and not supported by any rules.

Can it really be that easy?
I hadn't thought about this since its about studying . However the text can certainly be interpreted that way.
That's an easy fix.