One small extra piece of data. We can know that the Jane Tregion who married Edmund Bonville, had to be born in the period 1496-1541
This is because the Croker pedigree in that same source is slightly more helpful in stating that John Croker was heir to his grandfather and was "aged 25" in 1614 when this grandfather, also John Croker died.
The generation between these two Johns was Hugh Croker who m Agnes Bonville sole heiress of her father Richard who was son of this Jane Tregion.
We don't know enough about the Tregian family to say with certainty where Jane might fit in that family. We don't know how many John Tregians there might have been - of possibly different branches.
And I don't think you can say with such certainty that Jane Tregian HAD "to be born in period in the period 1496-1541". The only date you've given, which may or may not be accurate, is that John Croker (son of Hugh and Agnes Bonville) was aged 25 (i.e., born in 1589) at the death of his grandfather John in 1614. Beyond that, you're simply guessing at the length of generations in the Bonville family - which results in a pretty broad, and overly specific, range.
The same uncertainty with respect to placement in the Tregian family applies to Catherine, wife of John D'Oyly - and we have even less information on her.
As far as Tregian/D'Oyley goes..., remember back in February that mark66 gave the following descent as probably correct:
2b. Elizabeth Dannett married Sir John Arundell
3. Katherine Arundell married John Tregian
4. Katherine Tregian married Robert Doyley
5. Martha Doyley married Bartholomew Tipping
This was in the Bartholomew Tipping thread. Mark also wrote: "ODNB does note that Francis Tregian's father John was of "Golden Manor, near Probus, Cornwall", which presumably is the "Gouldein" referenced in the Vis. Oxon. The estate was lost to the family with Francis Tregian's recusancy conviction in 1579.
Vivian & Drake's 1874 edition of the Visitation of Cornwall (p 275) contains some will extracts for the Arundell family which both makes it clear that Katherine Tregian nee Arundell was the daughter of Sir John and Elizabeth nee Danet (d 1564) and implies that she had other children: Elizabeth mentions "god-daughter Elizabeth Tregian" while Jane Arundell (sister of Sir John) mentioned "niece Mary Tregian":
These, together with the Vis. Oxon., seem good evidence for the descent from John Arundell & E. Grey to Martha, the wife of Bartholomew Tipping; the 1632 PCC will of Martha widow of Bartholomew Tipping names 'my fift sonne Mr Doyly Tippinge' ..."