It is looking more and more like the religious separation of the Vaupel and Faupel spellings is local to Fritzlar. Or, more accurately, the retention of a consistent spelling of the two variants is local to Fritzlar.
As you noted, your Lendorf Catholic Vaupel/Vaubel/Fauble/Fable realtives have the name sometimes spelled with an F and sometimes with a V.
Iris Rohrback, who descends from Werner Faupel born 15 April 1744 at Niederjossa and who still lives near Niederjossa, told me that the same mixture of F and V spellings appears in the Evangelical Church records at Niederjossa (which is only about 18-20 miles from Fritzlar).
Prior to about the mid-1800's, most German church records that I have seen, as well as those that I have seen indexed on web sites or elsewhere, do not maintain consistent spelling of names. The spelling was usually dependent on whoever was writing it down, so that you will see the same person spelled one way at baptism, another at confirmation, another at marriage, various others at the birth of their children, and perhaps even another variant when they died -- all because the role of church recorder changed during the person's lifetime.
Lendorf is about 6 miles from Fritzlar, to the SE -- which is the same direction as Niederjossa, though only about a third as far from Fritzlar. So your information helps to see how far the religious split went beyond Fritzlar, narrowing it from less than 20 miles (which is what I knew from the Niederjossa information) to now less than 6 miles.
I also have relatives from Grossenenglis (GroÃŸenenglis), which is just 2-3 miles west of Lendorf. So we could be related through other lines as well -- Schaumburg/Schamburg/Shamburg, Theiss/Theis/Teiss/Tice, Simmon/Simon/Simmons/Simons. My records on this branch are in a box (which one and where?) in the garage. My sister and I sat in the pastor's home at Borken in 1981 and found a lot then -- seems to me that the relatives were spread in the direction of Gombeth, to the east of Grossenenglis, which is only about 1.5-2 miles from Lendorf.