As I see it, you could continue to use the OOB functionality (like you do now, utilizing the related list).
it’s supported, low-maintenance, and won’t turn into a custom UI project you have to babysit every upgrade.

Alternately, you could go in the direction of a custom built UI formatter (Remember all the logic you need to cater for in terms of it being editable vs read-only, and how it should handle retakes etc...) 
It becomes a tradeoff; "nicer" UX, but you’re building and maintaining a mini assessment app inside the form.

If you are keen on doing something to cater a tiny bit to the users; go with a small UI formatter just showing Status + "Take Assesment" link. That way you give them a bit of a UI "experience" with limited risk.