Rohais Campo de Tracy - Birth Date

I found this in Medlands. Lot to digest to make some sense maybe, maybe not. Scroll down to de Tracy. I am not sure either.

https://fmg.ac/Projects/MedLands/engunttz.htm

It seems Medlands have changed their view since this group of profiles were created and the name of the 'de Tracy' mistress of Henry is no longer stated:
WILLIAM de Tracy (-after Dec 1135). Guillaume de Jumièges names "Willelmus de Traceio" as one illegitimate son of King Henry I, adding that he died soon after his father[299]. The Chronique de Normandie, based on le Roman de Rou, records that "Guillaume de Tracy", seventh illegitimate son of King Henry I, died soon after his father[300]. [m ---. The name of William's wife is not known. William & his wife had one possible child]:

a) [GRACE de Tracy . The primary source which confirms the name and parentage of the wife of John de Sudeley has not been identified. Indeed, it is not even certain that his two sons were born from the same marriage: their adoption of the different names Sudeley/Tracy may indicate different mothers. Secondary sources commonly show John´s wife as Grace de Tracy, daughter of William de Tracy, an illegitimate son of Henry I King of England. This appears to be the assumption of many writers, for example The Complete Peerage[301]. Frank Barlow comments that "William [de Tracy], the second son of John de Sudeley…chose to take his name from the family of his mother, Grace daughter and heir of William (I) de Tracy, lord of Bradninch in Devon and illegitimate son of King Henry I"[302]. However, I have not yet found any writer who provides a precise primary source citation, which can be checked, to confirm this marriage. Her existence has been doubted by Professor Nicholas Vincent, who states that he could "find no reliable evidence to suggest that the royal bastard fathered a daughter named" Grace and suggests that Grace "seems to have been invented, perhaps in comparatively recent times, to explain certain irregularities in the Sudeley descent, and to justify the claims of the Hanbury-Tracy family of Toddington in Gloucestershire to be descended both from the blood royal of Henry I and from William de Tracy, the murderer of Thomas Becket"[303]. Until more information comes to light, it appears safer to note John de Sudeley´s wife as unknown, and show Grace in square brackets in the present document. m (before 1129) JOHN de Sudeley, of Sudeley Castle and Toddington co Gloucester, son of HAROLD de Ewias, Lord of Ewias, co Hereford & his wife --- (-before 1166).]

You have to start from what you know and work backwards. This is about the ancestry of the Champernons. What do you really know about Oliver's mother?