Currently, any user with a custom role cannot be designated as a collaboration coordinator. The only roles that are permitted to be collaboration coordinators are the default Facilitator and Administrator roles.
In our company, if we have entered into a collaboration with another organization, we want to allow our GIS analysts (those closest to the data and the project teams) to be able to own and manage collaboration group participants and content. The only option to do this currently, is to assign them a Facilitator or Administrator role.
If we were to assign our GIS analysts to the default Facilitator role, they would not have enough privileges to perform all tasking required as a GIS analyst (e.g. Facilitator cannot create notebooks). On the other hand, if we were to assign them the default Administrator role, they would have too many privileges that could impact the security of our organization (e.g. Administrators can manage the organizations security and infrastructure settings).
This means, a custom role is required to allow a GIS analyst work as a GIS analyst as well as manage access to project content as part of a collaboration.
