Given the increasing number of forum users, and the difficulty for newcomers without a social network of getting input on their posts, I thought I'd highlight this Facebook group (I have no affiliation to it, if that matters for a FB group).
It doesn't look very active, but I think if you post an open-access Google doc in there, many people will still receive a notification about it and potentially read your work.
Not very active, but asking feedback on any type of EA-related writing is also welcome in the #role-writers channel in the EA Anywhere slack: https://www.effectivealtruismanywhere.org/get-involved