You need to load world file (world.json) from SRMP saves (Slime Rancher/SRMP/[world name]/world.json) and editor will be loaded. You can select world or player in the left panel to edit specific object. An easy interface will open where you can edit stuff.
You can write about this stuff in Issue and Enhancement Tracker: https://github.com/TacoGuyAT/SRMPEditor/issues
You can clone the repo and do the stuff you want as long as the GPL 3.0 license allows it. Maybe I'll accept some pull requests, but i'm not sure, because there's a lot of shitcode I made already. Sorry.
You should dm me in discord: tacoguy#6813. P. S.: Please don't dm me if you want to translate it in russian and ukrainian languages.
Think about your money twice and then donate to Saty. I don't need money and I can't even receive it.