I looked at your role report. When your tidy-up is complete you'll be a master of FTH Synonyms. A couple things to note;
1. The agenda can display members not-attending without having a role to show this. Printed or emailed agendas have the option to include attending/not attending. You can open the editor on any agenda and click the 'Attendance' tab to see this as well.
2. Utilize the 'Role / Agenda Item Description' box rather than describing the role as part of the 'Role/Agenda Item'. This will help a lot with tidying-up.
First, set up your agenda template with the role names that you wish to display in your tidy-up. This is important before you begin to configure the FTH synonyms.
Utilize 'Repeated and grouped Roles' described in this document;
support.toastmastersclubs.org/doc/item/editing-an-agenda
The key tool for doing your clean up is Synonyms. See 'Role / Agenda item synonyms' in this document;
support.toastmastersclubs.org/doc/item/agenda-default-settings
Synonyms will make your historical role reports match the role names in your tidied-up agenda and retain the participation history of the members who filled those variously named custom roles.
Any roles for which you don't need to retain history can simply be ignored. (e.g. the attendance roles) They will still appear in role reports and eventually will be far enough back in history that they won't be a bother. (To prevent accidents with a members participation history, there's no method to delete roles that are no longer actively used.)