What happens when campaign categories are renamed?

Campaign categories can be named individually (Mapp Q3 > Configuration > Marketing Configuration).

If you change the name, existing reports, and analyses will continue to work. Also, if you use the campaign category as a filter, the change will be applied automatically.

Only if you also import campaign categories (e.g. via Excel, JSON, or data feed), you should adjust the name there as well. Otherwise, the import will fail.