Allow Users to Edit Published Newsletters?

Currently, I have several roles assigned (Manager, Editor) who don't have access to the "Edit" or "Delete" function on posted newsletters. Only my primary Admin account seems to have permission to edit these. I have all of the Permissions checked for edit/post/delete rights for these users, and also tried enable them via Taxonomy Access. Nothing works. Is there something that I'm missing?

I found the "SimpleNews Roles" module, but the unsubscribe bug makes it a no-go for me. Is this the only solution?

Thanks in advance to anyone who has some insight!
(If there is a solution that involves hooks and/or PHP, I'm a total neophyte when it comes to that, so you'll need to be very, very specific!)