How about the trade routes to England or Central Europe? Anywhere NOT in the direct-borders of the muslim world. I think Al-Andalus adopted Arab version because they too speak Arabs? Moors? Not sure.
I don't get the question here.
Al-Andalus had many languages, the prestige and most widespread one being Arab for said reasons, Berber for well...Berbers (critically the military) and mozarabic romance for mozarabs.
Outside Al-Andalus, as the Arabs wasn't the language of elite and of social progression, it wasn't used.
As I said, what would be the reason? Arab was the language of Arabo-Islamic political and social elites. Where this elite is not present, neither the language.
Muslim traders use Atlantic routes to London or "Holland" and want to spread their religion.
No, they didn't.
The traders wanted to make trade. And in fact, the islamic traders were mostly focused on mediterranean shores, while the most important markets were the northern ones (at least in Europe).
Add to that, the fact the islamic traders were often little but pirates and/or slavers for populations, an eventual message would have trouble to pass.
Historically, it was the latins traders that made the junction up to Al-Andalus, with the slave trade from eastern Europe by exemple.
Seeing that the population were already accustomed to Latin (or Celtic, but that's another matter), they translate the Koran into said language?
Did you read the posts? Arab is the language of revelation, and at the contrary of the christian Bible that state otherwise, Arab became de facto a sacred language.
And, even if they didn't care for religious reason (yeah, not religious reason for religious expansion

), you'll have that : Arabization was the scale of social progression in order to make the local elites less and less rebellious and more and more tied with Arab interests.
Allowing them to keep a cultural importance would have seriously delayed any safety regarding the use of local elites, and that would have been too dangerous, critically in Europe where the Arabs were a tiny, tiny, tiny minority.