Let’s talk about the conference app. Let’s assume there are 10 seats in one room for a Talk 1.
User A books 3 seats for Talk 1 by using the form button.
Is it possible to show User B who wants to book 5 seats for Talk 1 that there are only “7 seats available?”
Similarly, after User B’s booking, for User C - " 2 seats available"
In your events sheet, you should add a new column and use a formula to concatenate both the event name and the remaining seats. When no more seat available, you put something like "(full) in the concatenated string.
And then, in the calendar view, use the field of the new column for the event. It should answer your need to inform users about availability.