What are the main institutions for proficiency language exams for Indian languages in India?

From what I know

• Kannada Sahitya Akademi conducts exams at 4 levels for Kannada.
• No exams for Marathi except the school exams or doing a course.
• There are two exam conducting bodies for Hindi, in North and in South (I want to know which one is the harder).
• For Konkani the center is in Goa.

I know the language pool is massive but I am hoping to make a list of proficiency exams for most of the official languages at the very least.