Hi Cyril,
this is a very good idea to hide the date and show a custom text instead.
My sugests for handling:
In the component there could be a filter for showing and manage such hided events.
In the list such events could be shown first and a toggle button could hide or show such events.
In the calendar module there could be a extra link below or up to calendar, which shows in the popup window all these events.
In the list module there could be a toggle button to hide or show such events.
It would be great, if you work on this feature in the near future.
Regards,
Frank