Duplicate of note #3726955

Caerphilly Council has a leaflet which suggests 'Pontycymer' is no longer in use, hence the old_name tag, and the Welsh Language Commissioner also does not list Pontycymer as the current official Welsh name for Crosskeys

https://www.caerphilly.gov.uk/loopsandlinks/pdf/crosskeys.pdf

https://www.comisiynyddygymraeg.cymru/enwau-lleoedd-safonol-cymru

You mentioned it was listed on an 1813 map - perhaps you could map it on OpenHistoricalMap, providing that the map is out-of-copyright? 

https://www.openhistoricalmap.org/