I'd vote for the yogurt being fine as well. The applesauce is probably meant as a binder, and yogurt fits the bill well for that (in breads and muffins).
wrt applesauce..I must say that it's pretty uncommon around these parts. I like to use it in baking (or just to eat
), and it took some asking at the grocer to find it. There are only 1 or 2 brands at each store I've visited, and they're in the section with mint jelly, etc. That is, things meant to put on meat..bleah. It's very chunky and has lemon juice in it. Weird.
Contrast this to most any regular-sized store in the US, where there are at least a dozen varieties/sizes, probably more. Chunky/smooth, sugar/no sugar, with cinnamon, etc. in sizes ranging from small to gigantic.
When I was little, we used to make it homemade with a food mill.