I do not think the Didascaly has to be trusted as an historical account regarding the existence of Muhammad. But (has to be interestingly read) as regarding other things.
and not based on a detailed reading of the actual text, nor the scholarly commentary on it.
It is. The scholarly commentary on it say what it wants dear Mahgraye, what it wants...
Abraham’s source of information was based on interviews he had conducted, and this is very important, with “those who had met him [that is, Muhammad].”
Who are "those"? Whereas almost all Syriac accounts give how "those" guys are called, the Didascaly does not give any appellations, names, etc., about the "those". Where those meeting has happened ? When ? Blur.
The text reports that Muḥammad was preaching the return of Jesus. This information could have been known to Abraham’s informants, “who had met him”. And this quite explicit, since it says that Muḥammad came “with the Saracens”.
The return of Jesus is a Christian belief. Muḥammad is Christian ? Tell me he is, dear Mahgraye, and I'm converting to Christianity (the same as Muḥammad) at once!
The Didascaly describes a ("Saracen" as you say) Christian Prophet. It is what I read, dear Mahgraye. Came “with the Saracens”. But, dear Mahgraye, the Saracens, in Sinai/ Palestine/Syria/, they are there since 450 AD. And numerous. It seems that the Didascaly do not know that. How can that be ? And they are slowly converted from 450 to 600. To what ? Christianity (Jacobite).
I can think of three things: Muḥammad existing, that he preached the return of Jesus, and that he possessed the Keys to Paradise. All consistent with the later Arabic sources.
"All consistent with the later Arabic sources"
What "later Arabic sources"?
The Quran? Where, in the Quran, Jesus is returning, dear Mahgraye? Nowhere.
In the late hadith ?
It is then speculative theology ; nothing else. Not taken from the Quran, but from Christian creeds and scriptures (Book of Revelation). Same for Muḥammad with the Keys to Paradise, not in the Quran. The Keys to Paradise is a Christian concept. Nothing to see with Islam, Kaba, Zem Zem, Abu Bakr, the Companions, etc.
If Muhammad was alive and kicking, how can that be that the Didascaly is the sole testimony of a "meeting" with anonymous people who know him? Why do we not have other accounts like this ?
Mind it dear Mahgraye. Mind it.
It is because it is not an historical account.
I'll deal with Urwa later.