Goodness me, what a powerful and well-argued post; I wish I could have out it so well!
Yes, it seems to me that at the base of the ROCOR (and it does seem to be centred there) objections to ecumenism is a profoundly Russian phenomenon. On the one hand the Russian Orthodox have been used to being an Imperial Church and see themselves as the 'Third Rome' and as the inheritor of the Byzantine tradition; on the other hand, the Russians have long had a profoundly ambivalent relationship with the West.
There have been those, like Peter the Great, Catherine the Great and Alexander I, who have admired the West, seen it as more advanced, and wanted their backward country to imitate it; on the other there have been those such as Nicholas I and huge parts of the Orthodox Church who have seen the West as the spawn of Satan and something to be shunned as the home of all harmful innovation. When I see this in the Russian Orthodox Church, and then see it portrayed as 'the Orthodox mindset', I recognise the fatal confusion of ethnic practice and Orthodox praxis, and sorry for it.
We can deal with the filoque elsewhere, but my limited understanding of it is that there is one very particular definition of 'procession' which since it amounts to subordinationism, we would definitely rule out; but some of my Catholic friends tell me this is not what they believe. That may be so, but at least we are prepared to hear what they say they mean, rather than tell them what it is we think they mean.
The notion that we need to submit to their definition of the term Ecumenical Council, when many of the EO neither know what those Councils decided or what Ecumenical means is, of course, simply a hard-liners' device to avoid actually saying they do not want union. On a very simple basis of fact, if 'Ecumenical' means accepted by the whole Church, then nothing after Ephesus has that designation.
I think your analysis a shrewd and thoughtful one, and I find it intriguing and informative; we are all much in your debt for it.
In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. (1 John 4:10)