I like
Eilidh but agree the spelling is problematic. Still, dumbing it down wouldn't work because it would come across as a variant of
Kaylee (especially if you changed the spelling to Aylee). I think I'd keep it like this. If
Siobhan can work, then
Eilidh can. BTW, in our local paper, there was an article in there about a family (not sure what it was about) and all of the children had Scottish names. One of the girls was named
Eilidh. I thought that was really cool.