The mod crashes the server when I start with the 1.15 version (expected), will there be an update? Several players on my server rely on this.

Try the 1.16 build.

I'm dumb I thought this was the hwyla repo... Yes there will be a 1.16 version

https://www.curseforge.com/minecraft/mc-mods/simpleharvest/files/2989916

Not really sure what would have caused it to crash as nothing seemed out of place in dev, but there we go.