Summery: This should now work on any version between 1.12.2 & 1.16.1 inclusive. All future releases should as well.
Now I haven't tested all versions and subversion (because running that many different version servers and clients takes a lot of time) but I have added a 1.12.2 patch that gets applied when needed, and allows the plugin to work as if it was intended to be on 1.12.2. Since 1.13 and up are a lot closer to each other, not nearly as much was needed to do to make them work, and I didn't test everything, so let me know if there are any issues.

Speaking of issues, there is an error that commonly happens on shutdown, and while I do intend to fix it, its worth noting that it causes no issues.