Is the so-called "report after" even a reason?
I found JE's reason "report after" (if it's true) to punish Jin very stupid and unacceptable. It's fine a boss feel pissed because the employee didnt report to him before marriage, but it shouldnt be reason for the boss to put server punishment on the employee, as long as the employee's work and future schedule wont get messed up. The employee probably needs to apologize for not showing enough respect to the boss on the friendly base but it'll be illegal to take away several months salary from him just because he reported late.
In Jin's case, he's responsible for Meisa and he married her. JE took his job away and asked him to pay for the cacellation fee of venues which werent even cancelled by Jin himself, and froze his career when he has a family to support. They need a better reason than "report after". Jin only needs to apologize if he did report after and prepare for certain RESONABLE punishment.
It's not hard to get the conclusion that JE's punishment is not on "report after" thing but for marriage itself. The whole JE system is running on Mary Sue fans who want their idols to stay single for them. Marry young is to across the last line of the whole system and challenge the last authority of JE. This is the real reason and it's not beautiful because it sounds anti-human like.
All in all, Jin's punished for marrying young as an artist in a 21st Japanese society.