He participates in several online discussion groups about science. English is the language of the thread of those conversations, since it is the language most have in common. As soon as such a message is posted, another colleague will jump in and post a summary in English so that everyone can follow the thread. Sometimes these summaries evolve into discussions or disagreements about what the original poster actually meant. And if the topic is of great interest, a colleague might volunteer to do a full translation of the message into English for the group.
Many posters prefer to do their own translations, and so post messages bilingually.
HOW it is said, while we as English teachers tend to always be conscious of HOW things are being said.