I am only aware of this definition of unrolling. https://dictionary.cambridge.org/dictionary/english/unrolling To unroll something that is rolled. You could unroll a carpet out onto a/the floor prior to laying it, after having it delivered from the shop/factory to your house/home/apartment. I am not aware of unroll being used in slang or as an idiom/expression. "coming along well" also works more naturally in British English.

In American English, developing would be the right answer. I’ve never heard “unrolling” used in this sense, but we do use “unfolding” in this sense (unfolding also implies a sense of mystery, like you are not quite sure how the situation is going to develop, and so the result is a bit of a surprise). FYI, the most natural and common way to say it in American English would be “coming along well.”