Controlling Kodi

I did some searching to find out how to control Kodi.
I can start audioplaylists with the help of a function containing
return {
payload:
{
"cmd":"Player.Open",
"args":{
"item":{
"file": "C:/Users/Kodi/AppData/Roaming/Kodi/userdata/playlists/music/playlist1.m3u"
}

        }
    }

};
(Windows file system).
I can control play/pause by configuring a koni-node, placing
{"jsonrpc": "2.0", "method": "Player.PlayPause", "params": { "playerid": 1 }, "id": 1}
in the command line of the node.

I was happy and tried more.
Usind this description
https://kodi.wiki/view/JSON-RPC_API/v12#Player.PlayPause
i tried to turn on and off repeat and shuffle, trying it with
{"jsonrpc": "2.0", "method": "Player.SetShuffle", "params": { "playerid": 1 }, "id": 1}
Nope, did not work.

I'm also looking to control a seek +/- 5 and 10 seconds. Tried it with a similar sceme. No, did not work.

Can anyone help me please to correct read and interprete the API or has anyone a working example?

note that there is a kodi node with examples

This was my template to start playlists. But it does not show anything how to control all the other functions.