(I did try to explain to her that it was more related to my being left handed than my attempting to emulate European behavior. It didn't seem to make much difference to her.)
Or, it could be what my English son-in-law does, he uses his fork and knife, in different hands to aid in pushing food onto his fork. (He's right handed, not that it matters in this case.)
This explains the difference. The European method seems the most optimal.
On the other hand, I don't think Americans ever pick up food with their fork and switch the loaded fork to the other hand, especially if the food is scooped, not speared. A lot of food would be dropped in the process.
As a non-conformist, I taught myself to use my knife in the non-dominant hand so that the fork is used in the same hand regardless of knife usage.
It went underground - those who know just note that you're nekulturny, and move on.
They don't bother telling you about it, nowadays nothing good would come of that.