I'm not seeing if they were able to definitively say whether the milk fats and proteins they found were cow's milk or goat's milk.

Given that they found these in Bavaria, it's probably moot, as that's squarely in the area you would expect to find lactose-tolerating people, but everything I've read says that goat's milk has lower lactose levels than cow's milk. And, weak evidence, I know, but just about every piece of fiction I've read that featured babies that needed to be kept alive in the absence of their mother or a wet nurse has gone to goat's milk first - off the top of my head, this features in Ken Follet's Pillars of the Earth.