Could you please provide an explanation for \" llepa\" as appearing in the Street Name Caellepa
Formations like these tend to follow one of two forms they either follow the ownership of the land either by the family name or estate name or they are descriptive of the land itself.
In this case I would suggest the second is the most likely.
We already know Cae is field, and llepa is not a welsh name/estate that springs to mind so i'm tempted to say that 'llepa' comes from 'lletbai' meaning 'askew, sloping downwards'.
Further to confirm theory:
From: The Welsh vocabulary of the Bangor district (1913)
http://www.archive.org/stream/welshvocabularyo00fyneuoft/welshvocabularyo00fyneuoft_djvu.txtleppan, s., lledpen, D., ' side of the head ' : frppan d? ben di (O.H.) ; also leppan mmyS, * side of a mountain '. Cf. the Bangor place-name Cae Llepa.
Prior to the building of houses the land was owned by a Jane Jones who inherited it, releasing it for development around 1843
(Ellis Jones, “Bangor”)