Hello Dimitry,
As far as Llewelyn ap Cynwrig, there were actually 3 men of that name in cousin lines, all descending from the c. 980 Ithel ap Idwallon. Bartrum conflated these men, and if you will look at his Iestyn 14 chart (https://www.geni.com/documents/view?doc_id=6000000173392691854) you will see variances in the Gen #'s.
Most of the children are Gen 8. But one of those, Angharad, is shown as married to a Gen 6 Hywel ap Cynfyn Fychan. She should actually be a Gen 6, or possibly 7. We date her at 1215, the daughter of a c.1180 Llewelyn ap Cynwrig.
There are 3 more children that date to Gen 9 and belong to a later Llewelyn ap Cynwrig.
Now, a look at the wives of Cynwrig in Iestyn 14 reveals that Sioned (Jonet) ferch Cynfyn Fychan is charted as a Gen 6. It would be highly unlikely that she would be married to a Gen 7 man. We date her at c. 1205 as a second wife of c.1205 Llewelyn ap Cynwrig.
So, you are correct that the two profiles, Jonet and Sioned, should be the same person. Private User and I are slowly working through Bartrum's charts, but neither of us has gone through the Iestyn charts yet. Once we do, we can attach the various children to the correct Cynwrig(s). Until then, I will go ahead and merge the 2 women, leaving the children attached where they are.
As to the 3 men named Llewelyn ap Cynwrig:
Llewelyn ap Cynwrig c. 1235 descends from c. 1075 Gwrgan ap Ithel Fychan ap Ithel Ddu ap Ithel ap Idwallon.
Llewelyn ap Cynwrig c. 1205 descends from c. 1042 Gwrgan ap Ithel Ddu ap Ithel ap Idwallon
Llewelyn ap Cynwrig c. 1180 descends from c. 1045 Gwrgan ap Ithel ap Idwallon.
You can find a good explanation of this family in Wolcott's "The Conquest of Glamorgan-Further Notes" in the Appendix chart. (http://www.ancientwalesstudies.org/id226.html)
Good catch on the Jonet/Sioned mix up.
Cheers,
Steve