Hi,

Take this plugin as an example: https://umod.org/plugins/event-randomizer
Last update was three years ago, and the plugin have been broken for over a year.

Is it possible to report it, warn other users, etc?
If I understand correctly, the plugin help section/forum is a channel between the user and the plugin developer, right? So if the developer is gone, there isnt really any point making a report of the issue there.  

I have found that even though there might not be a response (and sometimes a negative response) the more complaints/requests made might convince a dev to take over the plugin , or make another plugin that has some or more features of the original.

The dev has been active for that plugin. did ya try to dm him?