Hi there,
We can have a Google Script that iterates over all calendars in the next x days and it will delete all duplicates. If two or more events have the same title and on the same time on two or more calendars, it will delete them except for one.
Also, we can use certain keyword to color events based on their categories instead of having many different calendars, for example, we can have another function that will run over your calendars, if an event title contains the word deadline, it will color it in red and so.
I understand the urgency of the project and I will do my best to meet your expectations.
I will be happy to address any of your questions!
Sincerely,
Mohamed