A few days ago I completed this mission along with my other character and one got the promotion and the rewards and the other didn't. When ever I click the door it just says that it is shut/locked tight.
I re-checked the full moon fountain to see if the fight was still flagged and it wasn't. I checked both the goblin and the npc in Windurst Falls to see if the cut-scenes for both the fight and the ending of that mission were enabled and they weren't. Mashua does not seem to have anything stored on him about anything mission 9 related as well.
The npc's Apururu and Kupipi both gave me dialogue as if the mission was completed successfully. e.g. kupipi, talks about having trouble finding the paperwork for rank 10 candidates.
The mission givers don't give an option to change / abandon the mission. Buuma's reply is "Naturally, I have been informed of Semih Lafiha's report to Chieftainess Perih Vashai--"
I tried to re-gather the ancient songs but it gives me a message corresponding to each area that it cannot be done. Also they are not in my list of key items temp or perm.