It is said that
Endelienta (Endelyn, Endellion) possibly Welsh Cenheidlon or Cynheiddon (с)
So, can Cenheidlon be derived from welsh "cenedl" (f) (plural cenhedloedd) - nation, kindred, family?
sources:
https://en.wiktionary.org/wiki/cenedl
https://www.behindthename.com/name/endelienta/submitted