I STRONGLY recommend that you take a look at this
list of authors and publishers to avoid. I have a number of the books on this list -- I got them specifically to see how bad they are -- and I can tell you that you're WAY better off just staying away from them.
Tom Cowan? Really? I got a good recommendation on "Fire in the Head" from someone on one of the ADF lists I'm on. I've had the book for a long time but haven't read it.
As for Frank MacEowen, I have some of his stuff. I wouldn't recommend it as CR, but I don't think they're bad books for Celtic Spirituality.
There's a whole range of Celtic spirituality between CR and utter crap. More work needs to be done illustrating those middle of the road paths, I think. There's a lot of good Druidry stuff out there, but not much else.
I understand where the hard CR folks are coming from when they diss books that don't fit in with their rigid models of celtic religion, but as someone who considers herself to be walking a Celtic spiritual path I often disagree with what CR folks throw out as invaluable.
Karen