Ironically, I was just looking at the 1937 Father Lasance Missal someone else posted here, and it indicates remaining kneeling from the Sanctus until Communion even at High Mass ... which nobody ever does anymore. Customs change. If I recall from the SSPX seminary days, some of the rubrics described here have been common in Europe for the longest time, so this may be little more than the SSPX trying to get everyone across the world on the same page (using Europe as the standard). In any case, since these changes are custom and can change over time and place, it's not really that big of a deal.
Once again you prove my point:
"Ladislaus response reminds me of the Novus Ordo mass attendees and the final trigger that causes them to leave and go to tradition. Ladislaus says he personally likes the rubric changes (though he does not identify the changes). Ladislaus wake up call level has not been reached yet. Others are more sensitive to the change and are protesting by leaving or fighting it.
If we are real traditionalists we should be consistent in our following what was always done, rather than accepting a change because "we personally like it". The issue should not be whether it is harmful, or whether we like it or not, the issue is whether we are changing a custom in our country. The issue is that the biggest contributor to the destruction which occurred in the post Vatican II church is the individual priests deciding on their own what is best to "improve" the way we worship. It appears to be a failing in the DNA of priests that makes them feel like they are alone in the altar and need the to constantly hear the faithful participating and moving about".
A simple "harmless" pill has side effects which can be deadly. The principle that a priest at his whim can change the customs of a country is what created the Vatican II church at the local church level,
the only place where the laity deal with the Church.
By the way, it is in the schools and the universities that all change/revolution is started. In the case of the SSPX in the USA, just like the Church in the 1950's and on, it is the grade school children at say, St. Mary's Kansas, and the seminarians at Winona that are taught the changes. It is then brought to the parishes by the young priests and the students teach the parents that they were wrong.
I'd suggest you read up on the subject, as there is no "European" custom, there are different customs in Spain, France, Germany, Italy...... the USA
By the way, France was the crucible of the liturgical revolution, in the 1930's and even earlier they already were changing everything. I doubt any Frenchmen exist who know what there traditions were prior. Moreover, France is hardly a country to emulate since 98% of French Catholics do not go to mass.
A "European mass postures customs expert" may just be an oxymoron.