So crossposting is working through my least favorite of the crossposting plugins. It doesn’t sync comments, doesn’t really update edited posts. It also doesn’t crosspost categories, only tags.
Nevertheless, it does work without completing wiping out the WP screen in error messages afterward.
While another crossposter works better and technically works despite the error messages, the error messages are just too many and make using the WordPress dashboard painful, so since I want everyone to be able to post, I opted to not use it.
That said, the active crossposter does leave an error message after a handful of functions, like editing a user. You are safe to ignore it and click the browser back button to get back to the dashboard. It does appear to save changes despite the error message.
I have yet to find any working crossposter that leaves no error messages at all. Despite my best efforts. 🙁 Sorry about that.
ETA: It also doesn’t seem to crosspost scheduled posts. Which means those will show up later on the Dreamwidth when I manually send them over, now that I know I must do that. 🙁0