There are a number of ways to talk about Greasy Fork镜像 and the things on it.
Do you have a question or comment about a specific script posted on the site? If so, post a discussion from the link on the Feedback tab on that script's page. Script authors get notification on their account page of any discussions on their scripts.
Do you have a question or comment on Greasy Fork镜像 itself or on script development, or do you want someone to make you a script? Posting in the forum would give you the widest audience for your discussion.
Do you have a bug report or fully-formed idea for Greasy Fork镜像 itself (and not a specific script posted on Greasy Fork镜像)? Post it on the GitHub page.
Do you have a private question or comment you would like only the admin to see? Send an e-mail.