Hi Chronitis!. To make sure your plot is 100% solid, you need to answer these questions:
1-¿Why the main character wants to become a bounter?, ¿to explore the world?,¿curiosity?, ¿wants to escape his country?, ¿greed?, ¿wants to be like a famous bounter he admires?, ¿to impress a girl?,¿adrenaline junkie?, ¿other reason?,
2-So, your main character ends up with a bounter badge from another person and screws up so badly the organization he accidentally represents gets blamed. ¿Why would they ask him to escort the person with amnesia instead of a more qualified person?, ¿why would they forgive him?
3-¿Why would bounters let an inexperienced person to travel with them? , ¿is he talented?, ¿he has a skill/ability the team needs?, ¿he knows about a valuable bounty?. Friendship in this case, may not be a strong reason (especially if it`s dangerous for the protagonist to go with them).
4-¿What you have to do to become a bounter?, ¿go to a bounter school?, ¿be mentored by another bounter?, ¿do a special bounter test?
5-If the requisite is a test or going to bounter school, ¿why the main character is not doing these things?,¿did he failed and there`s not second chance?, ¿he is too poor to afford it?, ¿is against the law in the town/city/country he lives?, ¿he is too afraid?
I hope this helps.