If you're talking about the potara, then you don't have an argument. There is no stated "potara multiplier" and it isn't stated that everyone gets the same boost. Again, this is entirely your problem, not the story's problem and it's not a problem from the power chain I posted earlier that the show has showed.
And even if Kefla and Vegito had the same "multiplier", it wouldn't mean anything because again you have to assume to substantiate your stance.
Just an example
Potara=a+b(10)
Base Kale: 1
Base Caulifla: 100
Lssj kale: 1,000
Base Goku: 100
Base Vegeta: 100
Ssb Goku: 10,000
Ssb vegeta: 10,000
Base Kefla: 1,010
Lssj Kefla: 1,010,000
Base Vegito: 2,000
Ssb Vegito: 200,000
So you haven't proved anything. Not that I think that lssj Kefla>Vegito but your argument makes zero sense. That seems to be the norm.
Lssj2 Kefla>Ssb Vegito. Period.