But the numerous reunions effected by the Catholic Church have been nothing short of miraculous.
For starters, there is a Catholic Church corresponding to every Eastern/Oriental Orthodox Church in existence. Belarussian Orthodox Church/Belarussian Catholic Church. Including some unique outliers: Melkites, Maronites, Chaldean Catholic.
These Catholic Churches "returned" to communion when their head bishops decided to rejoin after centuries of schism. Thereafter, these churches are open to new individual converts, as well as entire parishes or eparchies coming into communion anew.
Furthermore, the Personal Ordinariates were erected quite recently to accommodate conversions from the Anglican church. It began long before that: the Catholic Church has received Anglican priests, with their families, ordained them as Catholic priests, and set them to parish ministry. Yes, even the married ones. Some Anglican priests or bishops became prelates, and entire parishes converted to the Catholic faith. They even retain their own liturgy, "Divine Worship", which is based on the Book of Common Prayer. If you're a fan of the old Tridentine liturgy, just imagine if that were presented in English instead!
Today there are no fewer than 24 Catholic Churches in communion with Rome, including a brand-new Eritrean Catholic Church, corresponding to the split in the Ethiopian Orthodox Church.
So I disagree with your pessimism because we have plenty of examples, in the distant past as well as quite recent history, where Protestants and Orthodox alike have come back into communion with the Catholic Church. Thanks for bringing it up!