It's been a long long time, I've had a while to think it over and by that I mean I've rewritten the entire DLL component using the new Discord Activities API instead of the old Rich Presence one. Doing this also gave me the chance to recompile the project for x64-bit platforms as well, a crucial part in getting it to run on.. Essentials v19!
There are now TWO DLLs included in the download. One legacy x86 version, and a newer x64 version. For Essentials v19 you should use the x64 version unless you are sure you're not using the x86 version of mkxp-z. If you are working with a project that you converted to mkxp-z manually, chances are you will need the x86 version.
As far as I know there are no breaking changes between the versions, I've tried to keep the front end of the script identical despite the vastly different backend. If you encounter any bugs please let me know.
This also has not been restructured to support the new plugins system, sorry!