I am seeing a significant difference in the time it takes for Scriptable to complete execution within the app vs being called from Shortcuts.
This script, executed from Scriptable, is pretty much instant… maybe 1/2 a second before the Reminders list shows up:
var ProjectList = "abc"
Calendar.findOrCreateForReminders(ProjectList)
This script is called from Shortcuts and it takes about 6 to 8 seconds to complete:
var ProjectList = args.shortcutParameter
Calendar.findOrCreateForReminders(ProjectList)
This is my first attempt with Scriptable (the ability to create Reminders lists having just been added).
I have several shortcuts that work with Reminders. One calls four different apps before creating a list and populating it. This convoluted one is faster than the straight shot, one step, Scriptable Shortcut.
Please try to add Script.complete() at the end of the script. I suspect that will make a big difference
Scriptable attempts to determine when execution of a script have finished. For various reasons, this is more difficult when running with Siri and in the Shortcuts app. Therefore you can use Script.complete() to explicitly tell Scriptable that the script have finished.