What I personally do when I have to initiate a conversation with someone is:

1) Look at the profile and pick the language that the user is the most fluent in, and in which I can express clearly what I need to say without taking hours.

2) If the user didn't indicate anything in his profile, I look at his contributions and comments, and try to figure out what is the language that the user is the most fluent in, and in which I can express clearly what I want to say without taking hours.

3) If I can't find any common language, I write in English.


The language of the sentence is often a good candidate for the language of the comment, but it's not necessarily a language that the owner is comfortable with.

The problem is that writing to someone in language they're not comfortable with increases the risk of them ignoring your message (until they have enough time to deal with it).

As far as I'm concerned, I've received emails in German, Esperanto, Chinese, Russian, Portuguese, Vietnamese... I can tell you that most of the time, I don't read them right away. I tend to skip them and look at them only a few days later, or a few weeks later.

(en) When writing a comment on a sentence, I think it usually makes sense to write it in the language of the sentence. However, for something like Lojban with no native speakers, some other language would usually be the most appropriate. (Usually it would be English, but it depends on the situation.)

(es) Cuando se escribe un comentario en una frase, yo pienso que usualmente se debe escribirlo en el idioma de la frase. Sin embargo, para un idioma como el lojban, sin hablantes nativos, otro idioma usualmente sería más apropiado. (Usualmente sería inglés, pero depende de la situación.)

P.D. Si Ud. encuentra un error, dígame, por favor. ;)