What seems to happen in practice is that either: (1) If a majority of particpants are skilled in English, the less skilled will just submit the best they can,

What seems to happen in practice is that either: (1) If a majority of particpants are skilled in English, the less skilled will just submit the best they can, and the better speakers will correct (e.g. at patch-review time) anything too confusing in the same way they correct code bugs. (2) If the majority of speakers aren't skilled in English, you often end up with amusingly misspelled variable names and odd comment grammar, but most people can't tell the difference anyway, so it's cool.... [I work for a Japanese company, so many internal projects just use Japanese for most comments/commits (although I'm free to use English if I want, because most people can understand it more or less).... but because of character-set restrictions, variable names are still mostly amusingly-misspelled English...] E.g., there doesn't really seem to be all that much of a problem.