The hardest language exams in the world break your brain in totally different ways. Seems like these 3 pop up in lots of different contexts/threads:

1. Oxford’s All Souls Fellowship Exam

• A grueling 2 day experience where candidates must write essay after essay on philosophy, history, and classics, including translation tasks across Latin, Greek, French, Spanish, Italian, and "as many languages as one knew"
• An in-person interview where a candidate is questioned while surrounded by a ring of 50+ former and current Fellows
• The winners receive a 7-year research fellowship with free board at Oxford

2. Kanji Kentei Level 1

• The average college-age student in Japan has learned just over 2k kanji. This test requires memorization of over 6,000, including archaic, historical, and obscure forms
• Native Japanese adults rarely pass, with stated figures at <10%. Repeated sittings are normally required to earn a passing grade
• Considered a significant achievement even for scholars of Japanese language

3. International Linguistics Olympiad (IOL)

• High school students solve language puzzles in languages they often don't know or haven't been exposed to
• This is more of a reasoning exam than a proficiency exam, check out one of the problems from the 2003 competition in Bulgaria: