Why can’t I edit an imported calendar event here?

Why and what you can do

1. The connected calendar is the source for the event’s title and time, so Routinely does not make a separate conflicting edit.
2. Open the event and use Edit in source calendar if that button is available, or open the original calendar yourself.
3. Return to Settings → Calendar import and import events again. To stop seeing one event only in Routinely, use Hide from Routinely.