I cannot find where RCLPL got it from that a Powys daughter of Edward Powys and Catherine Jelf married a John Rogers of The Home, Salop.

A Penelope Powess was christened at Astbury, Cheshire on 4 Feb 1739, the same parish as Thos Jelf Powess’ baptism.  Is this the name of this unknown wife of John Rogers?

No.  As Penelope married a Thomas Cartwright.
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This is Penelope’s marriage, though:

First name(s) PENELOPE
Last name POWYS
Birth year 1745
Marriage year 1766
Marriage date 06 Mar 1766
Parish Astbury
Spouse's first name THOMAS
Spouse's last name CARTWRIGHT
Bride's age 21
Bride's residence Astbury
Bride's marital status Spinster
Groom's age 21
Groom's residence Astbury, Chester
Groom's occupation Surgeon
Groom's marital status Batchelor
Place ASTBURY
County Cheshire
Country England
Record set Cheshire Marriage licence bonds and allegations 1606-1905

It is possible that the couple’s ages of 21 is a mistranscription of ‘over 21’ and thus agreeing with the above baptism year and making her 27 at marriage.  I can’t imagine a chap being described as a surgeon at a mere 21, either.
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