What I did:
In a note, I tried to use the \reminder(Time of reminder, List: List Name) command by calling its French translation \rappel.
When I simply type \rappel, the reminder pop-up shows up and I can create a reminder. Same behavior as when I use the \reminder command.
But when I type let’s say \rappel(demain, list: Nom de la liste), nothing happens. The command is erased and the reminder is not created.
If I type \reminder(demain, list: Nom de la liste), then the reminder is created in the right list and at the right time.
Things that might be helpful to know (Agenda version, OS and model, etc):
On the latest macOS version. I didn’t try on my phone.