Using the tip provided by José Adan at http://social.msdn.microsoft.com/Forums/en-US/vstscode/thread/f6dec8c4-9752-4a9b-82fe-0822808fd386/ I was able to get Code Analysis to do spell checking in Brazilian Portuguese.
It's a common practice to mix Portuguese and English on type and member names down here in Brazil. I've also seen this practice in other languages in code originating from Europe.
So what I am trying to do is to enable both languages.
I searched around and after not finding anything I did some experimentation with things such as
<CodeAnalysisCulture>en-US;pt-BR</CodeAnalysisCulture>
and
<CodeAnalysisCulture>en-US&</CodeAnalysisCulture>
<CodeAnalysisCulture>pt-BR&</CodeAnalysisCulture>
Neither worked. The first one broke with a compilation error and the second one used the last language defined.
I'm almost sure Code Analysis does not support this, but as a last resort, I'm asking:
Does Code Analysis support defining two languages for mixed language Spell Checking?
PS: I'm already aware of custom dictionaries. It's my backup plan.