The Arabic New Testament does not use the same word for Jesus as the Koran does, however. The Quran calls him "Isa", while I believe the Arabic Bible calls him "Yeshua".
There would be no point in my examination of an Arabic text, as I wouldn't know if it said "Allah" or "Uncle Josh", since I can't read Arabic.
I do know that I've seen several instances of Arab Christians protesting that they do not use the word "Allah" to refer to God.
In any event, I hardly consider a specific translation of the OT to be "proof" that "Allah is God". If the translator(s) were ignorant of the history of the name of the god "Allah", and were instructed to use the word "Allah", then they would use that word, regardless of its inapplicability.
Let's put it into another context, since my "Lord Krishna" example flew right over the collective head collection here.
If you found an OT translation into some arcane middle eastern language, and saw that the word translated as "God" in English was translated at "Baal", would you therefore conclude that "Baal is God"?