Why would you put someone through something as humiliating as a college education, and their final exams? Presumably you want a measure of their knowledge and capability. In my system, no one has the right to become a representative. It's a job like any other, that requires non-standard admissions procedures (namely random sampling) to avoid corruption. I'm unsure if traditions could be enshrined to make my system stable, as it doesn't have a fiction as beautiful as the people's will to justify its existence. But I do think it's worth considering.

So how do communities gain appropriate representation in your system? Does everything come down to a test?

Maybe there could be 2 parallel branches, like the House and Senate, one of which uses this random sampling / testing system. The other uses something resembling a popular vote.