Are the Trigger Event Properties for an event only visible once that specific event exists in PostScript?

Yes, that's correct. The visibility of Flow triggers and their associated properties in the user interface (UI) is contingent on the specific Custom Event being sent to PostScript at least once. Here’s how it works:

• Event Initialization: When a new Custom Event is sent to PostScript for the first time, the system recognizes and registers this event.
• UI Visibility: Following this initial event transmission, the specific Trigger Event Properties related to this event become visible and accessible in the Flow builder interface. This means you can start incorporating these properties into your Flows.
• Implications for Developers: As a developer, it's important to be aware that you won't see the options for a custom event in the Flow builder until after you've successfully sent that event type to PostScript. This is particularly relevant during the development and testing phases when setting up new event types.

This approach ensures that the UI remains uncluttered and relevant, displaying only those triggers and properties that are actively in use and relevant to your current integrations.