I just read your post and wonder if you found additional information?
According to the 1871 Census, Hugh and Rosanna were living at Uchlawrcoed, Rhymney, with Hugh listed as age 77 and Rosanna as age 80. In this Census, Rosanna lists her place of birth as Llangwyfan, Denbigshire, but I have not been successful in finding any birth nor marriage information. Their children, William, Catherine, John, and Edward are listed in the 1851 UK Census as having been born in Llangattock, Breconshire, although they list their place of birth as, "Brynmawr". In the 1901 Census for Ystradyfodwg, Glamorganshire, son Edward, aged 60, is living with sister Catherine Johns, age 69, and Edward's son Hugh Coleman Williams, age 6.