I agree with your points and I can understand the desire to witness to the Jewish people and to acknowledge Judah as the lawgiver.

Calendar debates have been ongoing for centuries and I find it fascinating that it's even discussed in ancient Christian writings. Reading the Constitutions of the Holy Apostles, it talks about not computing the calendar yourself, but keeping the moedim with "your brethren of the circumcision".

Regarding the Passover:

Do not you yourselves compute, but keep it when your brethren of the circumcision do so: keep it together with them; and if they err in their computation, be not you concerned.

The context:

It is therefore your duty, brethren, who are redeemed by the precious blood of Christ, to observe the days of the Passover exactly, with all care, after the vernal equinox, lest ye be obliged to keep the memorial of the one passion twice in a year. Keep it once only in a year for Him that died but once. Do not you yourselves compute, but keep it when your brethren of the circumcision do so: keep it together with them; and if they err in their computation, be not you concerned. Keep your nights of watching in the middle of the days of unleavened bread. And when the Jews are feasting, do you fast and wail over them, because an the day of their feast they crucified Christ; p. 447 and while they are lamenting and eating unleavened bread in bitterness, do you feast. 3117 But no longer be careful to keep the feast with the Jews, for we have now no communion with them; for they have been led astray in regard to the calculation itself, which they think they accomplish perfectly, that they may be led astray on every hand, and be fenced off from the truth.