I see WAY more differences from scope to scope set at 12X than similar testing between 10X and 12X.
I few yrs ago I was SO pleased with my 10X SWFA fixed power rear focus scope that I bought a new 12X version as soon as it was available. A disappointement, as the 12X example I received was NOT better than the 10X, and in fact ranged a little worse, prompting me to sell it (I have since learned I might have been able to re-set the objective lense to gain better clarity and ranging on that one, bit its too late).
Anyhow, if your scope is very clear, and has a good reticle, it should work decent even at 10X versus 12X.
Along those lines, I observed 24X scopes often outperfroming 32X or even 36x in FT, due to small, but inportant differences in clarity and focus abilities.