For example there could be tests with questions from all levels of JLPT/Kanken and you can understand approximately at which level you are at from your results
Thanks - although I do not have plans to add this, as renshuu does not generally encourage a flat line upon which people can be placed. Most users do start off on the renshuu materials, which are level based, but just about everyone goes off onto tangents as they start to add materials that work best for them.
I know it does work for some people to have a test, but I don't think it's a good fit for renshuu given my goals and time constraints. I do appreciate the suggestion, though!