I'd like to read more about it. My understanding was that the vernal equinox for the Indian Orthodox was determined differently than in the other Julian Calendar lands, which made it a de facto revised Julian Calendar of sorts. Nevertheless, there were over two dozen calendars in India until the civil calendar reform in in 1957, which established one civil calendar and was followed by the Malankara Church. This would support the tradition of using the civil calendar.
I am not aware that the Malayalam calendar was used to calculate the vernal equinox, and thus the date of Easter. Everything I've read has claimed that it was the Julian Calendar which the Orthodox used to calculate the moveable feasts. In 1953, this was changed: the govt. did not want to give the people two sets of Christian holy days off (most everyone who works in India gets several religious holidays off, whether or not they are adherents of those religions), so they said we could either switch calendars and go with the Western dates so that everyone could be off and go to church or keep the Orthodox dates and not get the days off. Thinking it better to change dates and have everyone celebrate rather than keep the old dates and see few people at services, they changed calendars. I remember hearing somewhere (maybe Paul2004 can comment) that some Hindu holiday for which the schoolchildren were usually off coincided with Orthodox Christmas (6 January--I think this was before the Julian added a day), and so the vacation was called "Christmas Break" or something like that. I could be wrong about this, though.
Personally, I don't see anything wrong with the switch, given the reasons. Ideally, I'd like to see the old calendar restored, at least in America (where, I think, it might actually be easier to restore it among Indian Orthodox, all things considered). But as long as the calendar is consistent, not mixing and matching (like the Revised Julian), I think it can work.
The Orthodox Church by the 1400's had become unified in its liturgical practice universally by adopting a single typikon. The Russians made a specific effort to adopt the typikon of the Greek Church in the 17th century so that this unity would be maintained. Local Synods are not the Church in its fulness and as such should operate in concert with the other local churches. Having different calendars is a direct contradiction to the process by which for the previous 1500 years the various local practices coalesced into one universal usage.
I know you said you were bowing out of this discussion, but I will pose my question anyway, leaving it up to you whether or not you want to answer this publically. It is my understanding that the calendar is different from the Typikon (the book which tells you how to celebrate the services, what to sing, how to blend texts for different combinations of feasts, etc.). I have no problem with the entire EO world adopting a single Typikon in the 1400's; that is their prerogative, since they all share the Byzantine rite (regardless of anyone's opinions on our Churches, I
would hesitate to say that "the Orthodox Church" became unified in its liturgical practice, since the Copts, Syrians, Armenians, Ethiopians, and Indians, united in a common confession of Orthodox faith, were able to co-exist with different languages and rites, and, in this "smaller world" of ours, are no less able to do so--but I digress).
The universal adoption of the Sabbaite Typikon is not a dogmatic issue, and neither is the calendar. EOxy has within it a very small Western rite following: they don't use the same rite as the majority of their co-religionists, but I don't think anyone would doubt their Orthodoxy (unless one wanted to call the Orthodoxy of the Antiochian Archdiocese into question). Multiplicity of rites does not constitute a break in unity or necessitate a break in communion, and neither should a calendar. Furthermore, it seems to me that the calendar cannot be brought into this discussion, since the Julian Calendar was in existence long before there were schisms which cut off different liturgical families from each other. There was unity back then, as well as diversity.
Local Synods are not the Church in its fulness? Judged by what standard? According to Eucharistic ecclesiology (which you may or may not subscribe to, I am not sure), every local Church is the Church in its fulness, or is equal to it. Throughout the history of the Church, local Churches have issued guidelines for their own people, often without sending delegates all over the world to consult with the leaders of other local Churches about it--what you propose might be an ideal, but reality looks different to me. The example that comes to mind most quickly is the canonisation of saints. Properly, the recognition of saints is the prerogative of the entire Church. But local Churches often canonise locally, and let other local Churches decide about whether or not to recognise that for themselves and include them in their own respective calendars. It may happen in EOxy that this regularly happens over the course of time (that a saint from one local Church comes to be accepted and venerated everywhere), but that does not need to happen *before* canonisation occurs, nor do the other Churches have to investigate the matter themselves, or send representatives to the Church in question to join them in canonising the person. I think local Synods do have the authority to make disciplinary decisions for their own flocks independent of other local Churches, and this need not be a source for division. The wisdom of such decisions and the way they were/are carried out are legitimate points to criticise, but I am not sure we can say local Synods don't have the authority to make the actual decisions.