I have just read the latest developments with interest. I like a challenge!
Tyn y Coed Road is still there today. I love that area of the Orme and was very close to buying one of the cottages in Tyn y Coed Road some years ago. They were built for the miners of the Great Orme. I was told that they didn't know how old they are as the deeds went back to the 1760s but they were older than that. The garden with the cottage went up the back for about 100 yards on the Orme.
Anyway, I digress. I found a marriage in Conwy Registration District in the June qtr 1843, Owen Owens to Eleanor Jones. There is another marriage there in the June qtr 1849, Owen Owens to Ellen Jones. That looks the more likely of the two for your possible family. It might be worth getting the certificate to give you the names etc of their fathers.
The Owen Owens, aged 29 on the 1851 census looks to be the same person that was baptised by Owen Owen as an illegitimate son in 1821. Hugo posted the parish register entry for this and Owen was shown as of Gogarth too. Was Owen b1821 Mary's grandson?
The entry on the 1851 census suggests that Mary Owens died in between the 1841 and the 1851. I wonder if there was a will for her? I did try the Welsh Wills online site on the NLW but couldn't find anything. There are three deaths for a Mary Owen registered in Conwy in that period. In the December qtr 1842, Sept qtr 1845 and March qtr 1846.
In the 8161 census, Owen Owens is a Farmer of 21 acres, employing one man. This is at Gogarth Ucha, Llandudno. It reads:
Owen Owens, Head, Married, age 38, Farmer of 21 acres, employing one man, born Llandudno.
Elinor Owens, wife, age 30, born Llandudno.
John Owens, son, age 11, born Llandudno.
Mary J Owens, daughter, age 9, born Llandudno.
Sarah Owens, daughter, age 6, born Llandudno.
Ann Owens, daughter, age 4, born Llandudno.
Jane Owens, servant, age 38, born Llandudno.
The 1871 is an odd one and reads:
Gogarth Farm, Llandudno.
Jane Owens, Head, age 78, Farming, born Llandudno
Owen Owens, nephew, age 49, Farm servant, born as above.
Eleanor Owens, niece, age 40, born as above.
John Owens, son age 21, plasterer, born as above.
Ann Owens, daughter, age 14, scholar, born as above.
John Jones, visitor, age 76, Tailor, born as above.
It is interesting to note that the next dwelling is shown as Gogarth, followed by "Cottage". In the Cottage are your family of John Owens, wife Susana (born Llangwstenin) and five children.
Helig.