Roj, I also don't always agree with Merlin's take on the myth and have been dying for a Ringish telling for several years. However, I do like the premise and potential Merlin has established for itself. Yes I think the writers hurt themselves by resorting to stereotypical elements and too much retcon meddling, but when they decide to tell their mythos and stick with it for the second half of a season, Merlin is dang good.
Did you read my link? I think they should have gone with the getting dark and issues bits as concurrent storylines all season long. This show does not need creature features every week. Unfortunately, I don't think Starz' Camelot is going to be any better.
I imagine they must research, as the incantations are in Old English and Welsh are they not? Actually I think their premise for their take is quite sound. It's foolhardy that they deviate from what they establish for laughs and American desperation.