What you are missing is that we simply do not use compound nationalities because they are read differently by different speakers of English British vs American vs Australian etc Canadian American is ambiguous in some forms of English it means an American born person with Canadian ancestry which is not accurate Therefore we use the nationality held at the time the subject became notable in the lead sentence and mention any addition nationalities in separate sentences The problem is the ambiguity of the compound term Not all readers understand the same meaning you are attempting to convey This make the article inaccurate for a subset of readers Just don t use a compound term