I vote interfaces to make life simpler and improve scalability. This is a perfect use case for them.
The schema terminology will not read well until your overlook words like “implements” and think of them instead as “uses”
I have used the same Tag interface a dozen times in my schema. Not because every use case was exactly a tag, but because they all use the same fields. I may expand this later on as needed and break it into separate interfaces but when a single interface can serve so many purposes, why limit it.
Plus, I think* (haven’t tested or used it yet) that a type can implement multiple interfaces which will help bring down the schema size when needed.