That Saint just simply isn’t on the Roman Calendar (in the case of Photius…for obvious reasons).
If he was added to the Roman calendar by the Pope as Patriarch of the Latin Rite…the Roman priest could.
But while he can be locally venerated, that is to say, on the calendar, of even every single sui juris Church…that still wouldn’t make him universally venerated and papally canonized in the sense of an infallible declaration that he is an example of fullfilling all the normitive requirements of Christian life.
Of course even that could be done for Orthodox Saints before 1453. But I doubt you care if it is, since you have no similar concept.
For you, canonizations are only what they were in the first millenium. Local public veneration on the individual calendars approved by the bishops.
They do not carry the added status of being an extraordinary infallible declaration that the person is a good example of fullfilling all the objective requirements of the Faith. Which is not even the case for every papal canonization…the “cultus confirmed” ones, are mainly just recognition and approval of local veneration.
There are some good points about the way it is done now…but I would loosen it more to make a balance. I would have much more local veneration allowed to be approved by local bishops. The current process is way too Rome-centered. Why should every Saint, before being allowed to be added to Rite-wide calendars…have to also be a basically dogmatic statement? And even the ones added initially just to diocesan calendars…still need the Popes approval of beatification. Way to Rome centralized.
It wasn’t that grave in the first millenium, and should be made less so again. I think John Paul wanted to help go in that direction by canonizing so many…unfortunately, they were all still super-Rome-centralized canonizations except a few “cultus confirmed”…
There should be fewer pope-centralized canonizations (except for Saints who, you know, lived in Rome itself). They should be rarer and extraordinary (as they were from 1100 to 1978)…but there should be many more local canonizations like there were in the first millenium. People added by bishops to local calendars. They’d be merely passively approved by the Pope, without making any sort of extraordinary or universal statement, if they were from that diocese natively, and a bit more actively approved (ie, cultus confirmed) if the Saint was originally a local diocesan one, but was becoming popular and was proposed for public veneration in a different diocese (in which case it would involve the universal authority more actively as it involves more than one diocese). Some the Pope might want to add to the local Roman calendar, even the universal Roman Rite calendar…but this itself should often be just in the local sense as merely latin patriarch more often, except in really exceptional cases.