Hi Jan!
My previous title was "Member and Volunteer Services Coordinator". Membership and Volunteers were in one department - I was the primary manager/contact for our adult volunteers, but also served members. I think jobs in multiple departments are common, so some combined titles are necessary. It might have been more effective for my role to lead with with the word "Volunteers".
I feel like the word "Engagement" can be effective if it is not overused. I work at a University were our development department overused in position titles for development officers, and it confused some our our constituents. One of the roles was "Engagement Specialist"- that doesn't really tell anyone anything. The description of the title should be clear to the general public- you want anyone searching your website to be able to easily see who to contact, especially if they want to volunteer!
Samantha