One true churches and the other side’s saints
From FB:

I’ve noticed that Byzantine Catholics venerate post-schism Eastern Orthodox saints, and Western Rite Orthodox venerate post-schism Roman Catholic saints; can anyone explain why? I mean especially to understand the Western Rite view, whether WRV are allowed to pray to post-schism saints such as are contained in the Anglican Breviary...

‎90% of Byzantine Catholics don’t venerate post-schism Eastern Orthodox saints; they venerate the same saints as Roman Riters (they don’t identify with the Orthodox at all). A small minority, mostly converts, do. Which is no problem because Rome gives born Orthodox the benefit of the doubt: not heretics but estranged Catholics. (Maybe Antiochian WRO takes the same open-minded approach to Roman Catholic saints.) So you’ll find the tiny Russian Catholic Church (American non-Russians who love everything Russian Orthodox but remain under Rome) liturgically commemorating Russian Orthodox saints, with Rome’s blessing.

Anyway, my take on the subject. Rite controls what you do in church. (A kind of maintaining public order.) Your church’s bishops can only judge the holiness of people in your church so, except for what I described above, no liturgical veneration of the other side’s post-schism saints. Fair enough.

Private veneration is another story: outside of church you can venerate anybody. St Francis for example has just about universal appeal. Russians go to Lourdes (post-schism Western Marian apparition); there are Roman Catholics who love St Seraphim of Sarov. No problem!