Explain what constitutes a "Contribution"
In the "My Contributions" first page define what constitutes a contribution.
This could get long because the information should be exhaustive. It will have to cover why some changes are not contributions and others not. Examples are why is detaching a duplicate "Couple may have children" Research Help a contribution, while digging into a historical document to glean a date for the event and entering it into the source citation is not a contribution.
Near the definition should be simple, easy ways to suggest changes that should become contributions. Patrons could suggest changes maybe don't rise to the level of a contributions. Managing contributions could allow FamilySearh help steer patron's work in the directions that help FamilySearh achieve its goals.
MY CHANGES tab seems most relevant to your idea. In the Changes column you see various classifications of 'Contributions' - Sources, Person, Relationship - there are many. Relationship linkage makes multiple 'Changes' to Persons in the Tree. You can use OPTIONS to filter the view by Person or per Change.
You are right - it's not easy to correlate Changes to Contributions. For example Ctrl+F doesn't search the extended Changes list - only a limited way down the page. Perhaps you are wanting an 'indicator' for which Changes are 'counted' as 'Contributions'? I don't see the need to define what is a 'Contribution' - but it might help if there were an 'indicator' next to Changes that are counted as such.
For example, Record Hints are suggestions for actions that may result in a 'Contribution'. I notice Record Hint Rejected as one of the Changes 'types'. However, I don't know whether that 'Change' is counted as a 'Contribution'.0