Bill,
With the continued research into the Cland Maíl Ruanada origins, I came across this tidbit:
M1048, A predatory excursion was made by the royal heirs or chieftains of Ui-Maine into Dealbhna, where the royal chieftains were all slain, namely, Ua Maelruanaidh, Ua Flannagain, the Cleireach Ua Taidhg, and Mac Buadhachain, royal heir of Dealbhna Nuadhat.
Cruffon/Crimthaind (the baronies of Killian and Ballymoe in Co. Galway) was at least part of Delbna Nuadat, if not the entirety, and was a few miles to the north of Eyrecourt, so there could easily be 2 different Flanagan families in that general area. Given what seems to be developing with Cruffon in regard to the R1b-FGC5939 clade, it makes me wonder if you and Flanagan #FTDNA-IN72752 might be descended from the Cruffon Flanagans, while Gráinne's Flanagans just might be the Eyrecourt "Uí Fiachroí Find" family. It would certainly appear to explain the Y-DNA, if the Uí Briúin Cruffon connection holds up - why you are R1b-BY20602+ along with the McDermott and McDonough gentlemen.
Further, Flanagan #FTDNA-IN72752's MDKA origin, Williamstown, Corralough Townland, Templetogher Parish, Barony of Ballymoe, Co. Galway, appears to be right in the middle of Cruffon. The thing to keep in mind with the medieval Irish is that a territorial name was given based on the original inhabitants, and retained that name long after the original inhabitants had lost ownership or had moved on or died out. So it is very conceivable that by 1048 AD the inhabitants of Cruffon were Uí Briúin, not Delbna. Something to think about, at least.