I enjoy reading OP's stuff, especially since this is my branch. I'm bumping this hoping he gets a ping.
I can say that this seems to jive with my results. When I was looking over my STR results with a cousin of mine, before I understood things like str convergence, we both remarked that there seemed to be a link to the Hapsburgs of Austria (we are Spanish).The origin
The general theory is that V13/CTS5856 originated in the southern Balkan since it reaches its highest levels there. Based on recent analysis of V13*, CTS5856*, and its direct descendants, and some info about V13 in the Alps I think otherwise. It seems likely to me that CTS5856 and some of its oldest branches mutated in the border region of Germany, France and Switzerland, near Lake Constance and the sources of the Danube. In this region we find two V13* of the four we know.
One thing I'd like to ask is how you think the two Druze samples in this branch fit into the puzzle. Unfortunately, I can't produce any sort of matrix of relationships. For reference, on yfull they are my fifth and sixth closest result, after flags from England, US, Null (but known US), Italian, respectively, with the Swedes tied for 6th. The Belgians, Saudi Arabian, and Englishman in the Druze's group are tied for least shared SNP with me.
The fact that one is more closely related to the English kit than the other, as you point out elsewhere, precludes a recent founder effect. So what do you suspect continued to connect NW Europe to SW Asia?