I agree that it's taking an excessive amount of time for the final report to be released. Mind you, I guess it doesn't help when the aircraft manufacturer is tardy in providing data requested by the investigator. The interim report released last month states that it took the manufacturer around 12 months to provide some of that data.
If the report had contained an analysis of why the damage wasn't found for five days, then I guess it wouldn't have been labelled an 'interim' report. As the ATSB said in its 'Correcting the record' dated 14 July, the initial focus was analysing the safety issue that caused the accident in the first place, ie the opposing control inputs by the pilots. The investigation of the subsequent maintenance issues is ongoing and will be included in the final report, supposed to be released in December.