How can I get him to improve?
You are not setting a good example yourself (assuming the quality of your communication with him is similar to your question/comments here).
Being a native English speaker, your word choices and stylistic choices are not really the best either - including improper verb usage of your own (see this sentence -
His technical skills are pretty decent, but when it comes to communication it is miserable).
Why am I saying this? There are two reasons.
- You aren't perfect with English either (or are being intentionally quite ironic, in which case bravo!)
- If you still understand your coworker, why do you care?
This does reflect poorly on you (to me, at least) because you are asking a question and critiquing someone else's English and communication skills, while doing so relatively poorly. This context is completely different than a non-native English speaker effectively communicating but using a few wrong word choices...
I think this reflects poorly on my team and the firm. Also when he grows in his role, I think he will end up embarassing himself in front of a larger crowd.
My experience in working with non-native English speakers for a US based company (with those in Germany and India specifically) is no one cares as long as communication is effective. It becomes a problem when there is miscommunication about project work or other things.
Simply using an incorrect verb when the meaning is completely clear is a totally trivial problem.
So what should you actually do? My experience working with people in this situation gives me the following insight:
- Most non-native speakers are very self-conscious of their spoken/written English
- Most also want to learn but often don't even know when they are making those mistakes
I would suggest asking in an appropriate context (ie you actually know the person, if you don't have a level of interaction outside purely business, don't do this) "hey your English is pretty good, but you used run a bit awkwardly here, normally as native speakers we would use ran instead" and see where that goes - it will likely either be a "meh" or "oh, thanks! feel free to let me know in the future!" response.
Realistically though, unless this is actually affecting your ability to work (which it sounds like it's not) this is not something a manager will even consider an issue.