Yamato could be awakened but the reasoning is flawed.
It's a basic process of verifiability versus falsifiability. Whenever a hypothesis is proposed we should try to falsify it by looking for cases where the proposed claim is disproven instead of supported. In this case, Yamato's clouds aren't specific of the form we saw against Kaidou but is also present in the full-beast form, while Lucci's non-awakened forms seem to stay the same as before. Therefore, the claim that Yamato is awakened doesn't survive falsifiability.