Some sources have queried whether the term 'martyr' is appropriate for Catholics to use of the Twenty One murdered Copts. There is, of course, an implied criticism here of the Holy Father.
Any theological response to this query would have to take account of the fact that the calendars of "uniate" churches include commemorations of Saints who died without being in a state of full visible canonical unity with the See of Rome. These bodies include the (Melkite) Patriarchate of Antioch, the See of S Peter, whose Patriarch is, surely, the senior hierarch of the One Holy Catholic Apostolic Church after his Brother the occupant of the (other) Petrine See of Rome.
And any such response would need carefully to avoid any suggestion that Catholics not of the Latin churches are somehow not 'real' Catholics; or that the link between the lex orandi and the lex credendi does not apply to their liturgical rites to precisely the same extent as it does to the rites of the Latin churches.
Novi Martyres Coptici, orate pro nobis.