There’s an old adage:

“The way I learned it is the right way.”

Meaning, even if you were taught wrongly, you believe you are correct, and take offense at having someone telling you otherwise.

I get that.

But that’s not exactly what’s going on here. 

While there have always been slight regional variations, it happens that many of the liturgical customs in the French/Germanic countries were born of the liturgical movement (which by 1920 was no longer animated by Catholic liturgical principles). 

So it’s not firstly a matter of French vs American preferences, but traditional vs modernist praxis.

My guess is that the French of 1850 would not find agreeable many of the things which pass for traditional Western n France in 1950 (ie even in some French and Germanic SSPX chapels, where the Gospel and Epistle are read at the altar in the vernacular, etc.).

THAT’s the primary objection to importing French liturgical customs to America: It’s not that they’re French, but that they’re modernist.

I am glad you raised this. I am working in a paper on this issue. I believe that the priest had no right to change custom after 40 years. I have the same problem in Florida. SSPX Florida has been doing it the French way(for lack of a better word) for quite some time (but not over 30 years). I would suggest that your group of 4 or 5 continue the custom the old way. If you do not , the custom will end and a new one begins. Custom after a period of time becomes law. Under the Canon Law custom can become law and cannot be changed except for serious reasons. Just because there are a group of priests who want to change the posture orders does not give them the right to do it.