Yes, it is somewhat pseudo-random if they will evolve or not. Luck-based things and all that. :]

With regards to the 'strongly resonated' messages, yes, that seems normal. Some creatures will not resonate strongly to any of the actions, unless their 'face beams with the light of pure contentment' (this includes critters that normally don't like being interacted with at all, but will like it during that time).