I have no access to stellaris atm, but my thoughts are:
- Who triggers this event, when and for whom? Because it is is_triggered_only = yes, which means it does nothing on it's own. Either remove that or have somebody trigger it on all countries.
- Since you are in the country scope already, and either way owner_country does not exists, so just do that: save_event_target_as = owner_country. Or even you can remove all owner_country.
- Can a faction really be owner of a wormhole station?
Do you know if we're actually able to create our own variables and/or classes?