I thought that as well for a while so I was waiting for someone to say that! My claim that A is exactly ℵ2 is based on it saying "unique", meaning there's only 1 cardinality with the property described, between ℵ0 and A (which must be ℵ1). But I agree the wording is not very clear. The version without uniqueness is still a dilemma, it just means that it's also possible for A to be larger than B even if CH is false.