"Torque-oscillation" on the 412 can have many reasons....SAS/ATT FD are only one....
Tail rotor balance issues, Hydraulic issues, FT issues, pilot input, Throttle feathering, Mast mount issues and many more are just a few things to start looking at.
I know this is not an issue with most companies-but thats one advantage of a company having a properly trained maintenance test pilot working closely with very experienced engineers-those crews are most times able to detect and solve smaller issues before they result in something bigger (or-let alone-catastrophic...)...