Eira and Eirlys won't work because you will get Ay-ruh or Ira, and Air-liss or Errliss, Eyr-lees etc.
Not keen on Dilys.
Delyth is probably in her 50s or 60s, so a granny name.
Gwenie isn't welsh. Neither are Gwennie and Gwenna.
Gwennol is nice.
Efa will be pronounced like heifer without the h.
Rhian is dated IMO, likely to have been at school with Delyth. It is pronounced RHEE-ann not Ree-Anne, or REE-un.
Cariad is awful. It is pronounced CARR-yad not Carry-ad. It isn't a name, it's a term of endearment.
Cerys will be Cerise or Serris.
RH is a single letter is welsh and sounds like R and H being said at the same time.