Podes verificar na ajuda do site que a ideia é poderes perguntar nas duas línguas, mas sugere-se que se pergunte e responda em português.
No meta, tanto quanto sei deve-se escrever em inglês para que toda a gente possa compreender e discutir os assuntos do site e para facilitar a vida aos CM's da rede SE.
Should I write in Portuguese or English?
Both languages are accepted. If you are learning Portuguese, we
suggest that you learn by doing and ask in Portuguese, but there is no
obligation. When answering a question, we encourage you to answer in
the language of the question, if you are able. Don't worry about
making a few mistakes: other community members can help with
corrections if you are not as strong in that language.
Note that some contributors prefer to answer in Portuguese, so you may
get replies in Portuguese. Posts made in only one language may be
translated into the other one by community members for wider
On the main site, all tags should be in Portuguese unless there is no
Portuguese equivalent for a concept; then English is accepted. On the
meta site, tags should normally be in English.