thanks for taking the time to look at this and respond. Any information on Owen's origins is still proving elusive although a little progress has been made since the original posting.
Namely, I am pretty sure that I have found his death. It appears he died 28 May 1842 in Gaerwen and was buried 31st May 1842 in Llanedwen Parish. Where is still not clear and efforts are being made trying to establish this and whether a grave still exists.
As you rightly point out, the family did live at Glan Llyn for some time according to baptism records found for the later children of Owen and Elizabeth. In the early years however the family appear to have moved around a little.
The first child born was a Robert Owen Roberts circa 1820 in Bodwrog but no baptism record found to date; the second Ellin in Llanbedrgoch where she appears to have been baptised on 10 March 1822; and the third Benjamin born Bodedern circa 1824 - again no baptism record found thus far.
Certainly from approximately the birth of their next child, a daughter Mary in circa 1826, Llanfihangel Esceifiog appears to be home. The family also appear to have embraced the Calvanisitc Methodist religion around this time (if not already non conformists) as many of the later children were baptised in Gaerwen. There appear to have been 11 children in all and I am descended of Hugh born 1838 in Gaerwen.
So the challenge still remains who were Owen's parents and siblings and indeed who were those of his wife Elizabeth (nee Williams) born Bodwrog circa 1801. Elizabeth herself appears to stay in the area after Owen's death and was it seems living alone at 3 America Street, Gaerwen by the time of the 1871 census. (She appears in the 1851 census as Ellin Roberts)