Just shortening copyright would mostly mitigate this issue. If it was 10 years after creation then the most you have to wait is a decade. It may be nice to also

Just shortening copyright would mostly mitigate this issue. If it was 10 years after creation then the most you have to wait is a decade. It may be nice to also have a specific exception for "abandoned" works but at least 10 years would be a solid fallback with no need to do difficult research like finding the authors and if they have died or proving that a work qualifies as abandoned.