NoD
It depends what your exact idea is of primary causes etc.
The primary cause may well have nothing to do with the standard of English in this incident - the primary cause was in fact more likely to be down to the non alignement of IRS (coupled with the fact that the crew did not ralise this).
What was a major factor in the resultant way the incident played out was the poor English - exacerbated no doubt by the stress the crew were experiencing.
In this respect, the poor English was a primary factor (and some would argue it was the main factor by a long way) in the way the incident snowballed.
I have listened to the actual R/T and watched the radar replays twice now - I can assure you that had communications been clearer, the incident would not have caused so much of a problem.