I've done a lolita Pikachu so when I hear the term "cosplay lolita" I associate with that sort of thing. In the end, this outfit is a cosplay I just did it in a lolita style. Despite it being a cosplay I was still careful to follow lolita guidelines.
On the person wearing brand calling it a costume, it depends on the situation. Are they using it because it looks similar to something a character wears? If that's the case, I wouldn't see it as any different than someone putting a cosplay together with stuff they found at Forever 21, other than the amount they paid for.