Did you use that mash schedule (the one you linked to) for both the millet and the buckwheat?
I am basically just mashing using the same temperature steps recommended for the Promalt I was using. I've seen sources suggesting that one can make beer using buckwheat without cereal mashing or adding enzymes, but I definitely don't observe what looks like gelatinization until the temperature gets close to boiling. Additionally, Twila from Grouse has told me that she believes buckwheat needs to be cereal mashed first. And yet, most malt analyses I've read on buckwheat suggest it has higher DP and higher extract potential than millet malts, which is very weird.
Frankly, I'm not convinced there's a benefit to using buckwheat malt at all. I haven't noticed that it contributes much of a flavor, it may even have less of one than unmalted actually. I've used it in a lot of beers and never really been able to pick it out; it is easily dominated by just about every other ingredient.
Also, I've been using pale millet malt from Grouse, not CMC; just got some of their red millet pale malt and want to see how it compares. I'm wondering if Grouse's pale millet (which is made from white proso millet) isn't simply a superior product, more fully-modified or something.