My best guess on the "-leigh" = "-lee" thing is the surname
Leigh, particularly in reference to
Vivien Leigh.
Years ago
Lee was both the male and female spelling. Then people began using
Leigh for a girl, which is backwards to me because surnames feel more masculine than feminine to me. But I digress.
Anyway, that's the only way I can reconcile "-leigh" being pronounced as "-lee" at the end of created names.