Please! I just tried to do this. The calendars seem to be in random order.
Ordering them myself would be very good.
Even alphabetical would be more useful than random.
Please.

This is one of the features why I am not sure whether I want to use premium Proton Calendar or Proton Unlimited... If I use several calendars for different projects I want to be able to sort them. This allows me to access what I want quickly, as well as display or hide different calendars in an easy way depending on what I am working with.

This is very important to important to me I have many sub calendars to organize. I use planetary transits and they take up so much space. I would like to toggle on and off and reorganize my calendars the way I want to look at them. I was moving my google calendar first, since it is the least complex, now it holds the top spaces and is the least important.

A way to adjust the order of the different calenders how the appear in Proton Calender, like folders and labels in Proton mail. Or order calenders automatically via numerical/alphabetical order, like in Google calender.

customize order of calendars in ProtonCalendar...
self explanatory - ProtonMail has these features already, so I suppose analogous changes should not be too time consuming to implement them properly.

ps: also, share only a time window of calendars, not all or nothing.

I would like the reorder feature for the calendars, too, but it could be just like reordering the folders in ProtonMail.