I am starting the Temari Level 3 certificate which is classified as Teacher. To officially teach Temari is Japan, this certification is required. FYI, Level 4 makes you a Master or Professor; I don't know if they would use the term Sensi for L4.
For this certification are about 11 temari to make; of which 12 temari plus 8 new patterns and the temari from the patter are required. The all the patterns and 3 of these temari are sent to Japan to be kept by the Japanese Temari Association; sometimes they sell the temari to raise funds.
I have to work on this for at least 2 years before I can apply but it may be closer to 3 before I actually do.
Here is a temari I just finished for fun; it is not a temari that is required for the L3 certification.