So, the current situation is the following:

| Type of entry                                                              | Face                      | Use `org-agenda-timerange-leaders' |
|----------------------------------------------------------------------------+---------------------------+------------------------------------|
| simple date: <2023-01-01 Sun>                                              | org-agenda-calendar-event | no                                 |
| simple date with hour range: <2023-01-01 Sun 10:00-15:00>                  | org-agenda-calendar-event | no                                 |
| timerange (same day): <2023-01-01 Sun 10:00>--<2023-01-01 Sun 15:00>       | default                   | yes                                |
| timerange (different days): <2023-01-01 Sun 10:00>--<2023-01-18 Wed 15:00> | default                   | yes                                |
|                                                                            |                           |                                    |

and you say it would be better like this:

| Type of entry                                                              | Face                                      | Use `org-agenda-timerange-leaders' |
|----------------------------------------------------------------------------+-------------------------------------------+------------------------------------|
| simple date: <2023-01-01 Sun>                                              | org-agenda-calendar-event                 | no                                 |
| simple date with hour range: <2023-01-01 Sun 10:00-15:00>                  | org-agenda-calendar-event                 | yes                                |
| timerange (same day): <2023-01-01 Sun 10:00>--<2023-01-01 Sun 15:00>       | org-agenda-calendar-event                 | yes                                |
| timerange (different days): <2023-01-01 Sun 10:00>--<2023-01-18 Wed 15:00> | new face (org-agenda-calendar-daterange?) | yes                                |

Is that correct?