Looking at your questions many seem to be asked from your belief that I believe I am more righteous or holy than others because I advocate for Christians keeping the holy days of the Lord Jesus Christ. That is incorrect.
I'll answer your questions but let me ask a couple of my own.
1. Do you consider it a fact that traditional holidays are more important for Christians to keep and observe than biblical holy days?
2. Do we as Christians have an obligation to our brothers and sisters in Christ to point out when they've strayed from the teaching of the Lord?
Yes, we do. However, we then must be ready for THEM to "point out" when YOU have strayed, be it ever so small a deviation.
It could turn REALLY ugly in a nanosecond.
It could be ameliorated by a joke of some kind: "Missed Sunday Mass? I hope those Packers made it worthwhile for you. No? Well, there IS always the confessional."
If one is a non-Catholic Christian then one ONLY needs to say "Sorry, Lord" and it's forgiven, even if one sins 100 times a day. PIECE OF CAKE.
Sin isn't a problem with that solution...no confession, no penance, no intention of not repeating. EASY PEASY.