I think the confusion comes from the fact that you can indeed create a reminder for today in a template note (tip, you can also add the “title” parameter if you want the reminder to have a certain title), but you can’t create a new event from a template. You can only go the other way, from an existing event you can create a linked note from a template, and when you do so the event-notes and event-title parameters are filled in from the (existing) event you create the note for.
For now if you want to go the other way (create a new note and a new linked event to go with it), it can only be done on iOS/iPadOS using the Shortcuts app in combination with x-callback-urls