Things to focus on to improve your feedback wording:
👎 Bad Feedback - John does a really poor job of communicating when we've worked together on projects. I'd like for him to work on this in the future.
👍 Good Feedback - Over the past week, John and I have not connected when we needed to in order to execute the latest campaign. I made several attempts to ping him on Slack as well as approach him in person but he did not work with me to set aside the time we needed to collaborate effectively. This lead us to continue down a path that prevented us from being totally successful. If we were able to schedule a solid meeting time I'm sure we would have done a better job of staying on track and delivering a higher quality campaign.
Here are some write ups we've put together which might be helpful...