The Scottish Executive did not amend Westminster's Act, it changed its own name to one which most Scots recognised and preferred. That Westminster proposes to recognise this de facto change of name must surely close this discussion: the change of name is effective.
I have no knowledge of the enquiry you mention. No doubt the response given was due to the fact that the FCO has the most convenient translation facilities. I daresay a similar response would have been given if the same question had been posed about enquiries in Welsh, Irish or Manx. But, in case you argue that the Isle of Man, Northern Ireland and Wales are all foreign places too, what about Cornish? Would the answer be the same in that case? I expect so.
The answer would also have to be the same, I imagine, if British speakers of Urdu or Polish sent in an enquiry.
The inability of Westminster to function in any language other than English (since it forsook Norman French and Latin) is its own shortcoming, born of its Anglo-centric arrogance.
Gaelic came to Britain long before Scotland came into being - at a time when (probably) Pictish or Cumbric was spoken. It descends from Irish, agreed, and has probably only separated from that language in the past few hundred years, but it is a language that has been native to modern Scotland for at least as long as Scots, English and the original Anglo-Saxon, and for much, much longer than Urdu or Polish. That, I believe, is the key.
I do not for a moment overlook the SNP's aims, and my heart, if not my head, supports them. I certainly believe Gaelic is entitled to the same recognition as Welsh. As the SNP are the party in power at the moment, and all of the unionist parties are in opposition, does that not suggest something to you? Instead of cavilling about what they choose to call themselves, and the language they choose to do it in, offer a better alternative, or watch Salmond woo the electorate away from England. Probably with England's fond blessing too.
As for Megrahi, the Scottish Government did nothing it had no power to do, and what it did do was within its powers, regardless of who was or was not watching. If you're blaming Salmond for seeking political attention, there are hundreds of other reasons to attack him for that, just as there are for attacking Goldie, Gray or Rennie.