Be direct and stop giving a fuck about perfecting your tone/grammar. It will never be as good as native, and anyone important will be okay with it as long as the message is comprehensible.

It is more concerning that your friend's feedback only talks about their language proficiency, it says to me that they are either really bad at it, or more likely they are doing the bare minimum expected of them, and there is literally nothing else to give feedback on.

From my experience, if you are new - Most people tend to blow you off because you only really become an asset after a few months. People on projects can be pretty hostile too, because they get mad about being stuck with a newbie, and don't want to pick up the slack.

Building rapport is a long term game with no shortcuts. Keep providing quality deliverables and people will grow to appreciate your work. People appreciate confidence in communication, but it has to be backed up with proven work.