Sorry it took so long guys, but here I have a new version of the plugin:
Spil Games API plugin 1.2 Beta
The plugin has a property now which lets you enter the ID you get from Spilgames for your game. For the splash screen there are is a new action "Request splash screen", which does exaclty what you are guessing. Also a condition "On splash screen end", which will fire when the splash screen is done showing.
You may disregard the older splash screen stuff. It's merely still there to not break existing projects.
I'm labeling this still a beta because I couldn't really test the part with the ID. Any feedback on this would be great.
I will update the first post of this thread at a later point when I can fully confirm functionality. For now grab the beta from here. Thanks!