Given that at least in ROCOR, our churches in the majority Byzantine rite commemorate the authorised saints of Western Orthodoxy in every liturgy
Don't assume that other local churches are as advanced as ROCOR. I've yet to see at least one Scandinavian saint in Finnish Calendar.
why do they not call the Liturgy the Mass as is the norm in western tradition?
That's a really good question which also I have been wondering. That could be some kind of minor byzantisation.
While I'm against all byzantisations of WRO, I have a gut feeling that Roman Patriarchate used to be a little more Byzantine than post-Schism RCC. It's calendar and fasting rules (and liturgy) could have been suprisinly similiar with other four patriarchates. It could be a proper compromise to recover these traditions since they are genuinely Western and Orthodox and could also make WRO more acceptable to Byzantine faithful.
One of the things that stands out about the Western-rite is the need to recover an understanding that the pre-Great Schism Latin Church was Orthodox, and I suspect there is a much greater need to appreciate Roman Orthodoxy with it's Latin cultural and spiritual heritage which includes the use of Latin.
There is so much preoccupation with "ye-olde Celtic" amongst some WR advocates. Celtic is used very loosely by some, with some even implying that it was the norm of pre-Schism western Europe, relegating the Roman or Latin to a secondary position. It would be an irony if the Byzantine rite Russian Church offered greater respect to the non-Celtic Western Orthodox saints than many in the Western-rite.
Archpriest Andrew from ROCOR UK's Diocese notes in Orthodox England in relation to Latin Saints of the Orthodox Church: "We use the term 'Latin Orthodox', since the term 'Western Orthodox' is too confined geographically. It also has connotations of 'Western-rite'. Even the term 'Western European Orthodox' is insufficient. We use the term 'Latin Orthodox', because the term includes all those holy ones who were part of the Roman Patriarchate. This includes all those who used Latin as a liturgical language, from the Atlantic Celts to the Scandinavian Norse, from the Germanic peoples to the Latin peoples, from Eastern and Central Europe to North-West Africa.
The latter have been particularly neglected. Only the ever-memorable Bishop Nathanael in his reports in 1953 and 1954 to St John the Wonderworker, wrote to any extent about the saints of Latin (North-West) Africa, as opposed to Greek (North-East) Africa, who were centred around the Patriarchate of Alexandria. We should not forget that the native peoples of North-West Africa, the Berbers and their descendants the Kabyls, spoke Latin, not only before the Muslim invasions, but right up until the twelfth century."http://www.orthodoxengland.org.uk/saintsint.htm
The first fifty-three popes of the West were and are Orthodox saints. To St. Zacharias the Pope (d. 752) 68 out of 90 were saints of the Universal Church. http://www.orthodoxengland.org.uk/ortpopes.htm
Similarly in England, so many Archbishops of Cantuar (Canterbury) were and remain Orthodox saints worthy of the highest veneration in the Eastern and Western-Orthodox Churches. St. Augustine of Canterbury, Apostle of the English (604), St. Alphege, Martyr, Archbishop of Canterbury, (1012), St. Dunstan, Archbishop of Canterbury, (988), St. Theodore, Archbishop of Canterbury (690) point to the sanctity of the bishops of the See of Canterbury. http://www.orthodoxengland.org.uk/natlocst.htm
I cannot understand the preoccupation with the Celtic past, which some take to the extreme of talking of "Celtic Orthodoxy". The other extreme of the Celtic nostalgia is out and out paganism, something to be avoided under the trappings of the New Age. There is much to re-appreciate about the Western Orthodox past of Europe, but it will not achieve anything meaningful if it is lost in Celtic fantasy or Western resentment towards the Byzantine dominance of the Orthodox Church. There appears to be clear evidence of Greco/Coptic monastic presence in Celtic Ireland, and it would be useful to know what level of Byzantinisation of the Irish Church occurred in those times.
It is a noble thing to seek to take the DNA of Western Europe's pre-Schism Orthodox heritage and fidelity to the Faith and bring it back to life - but it cannot be done without acknowledging the loss of Orthodoxy in all of Western Europe - including the so-called Celtic lands. Orthodoxy was lost in the West and the West was fully lost to Orthodoxy before the restoration of Orthodoxy by the Byzantine priests and missionaries of the Russian, Greek and other national Orthodox Churches.
The Western-rites are entirely reliant on their Byzantine bishops, and Synods etc. Logically if the Western-rite is to have any meaning apart from some kind of Uniate life in the wider Orthodox Church, it requires it's own bishops and theological seminaries and a much more robust infrastructure of parish churches. Without this the Byzantinisation of the Western-rite I suggest is inevitable, however this does not mean a lack of love and respect for the Western Orthodox traditions and saints by the bishops, priests and faithful of the "Eastern" Orthodox Churches.
It is the Byzantine rite Churches who have breathed life into the defunct and spiritually moribund West. It is the Antiochian and Russian Churches in particular which have promoted the veneration of those English and other Western saints, for whom veneration in the West was largely extinguished for centuries. A shared liturgical and fasting calendar is logical for the Orthodox East and West - and especially because 99% of Western Orthodox Christians are not Western-Rite but worship in the Byzantine-rite, happily, comfortably and gladly.