As for ambiguity .. I mean it does not work well with sonar autocrew, which I switch on time to time. Especially on Kilo sonar AC is very useful, since Kilo only have 2 trackers.
But back to TA. Sonar AC will remark false contact each time he finds it. On FFG you simply select which contact is false and AC wont change it, only sometimes if you marked it wrong
For manual sonar there is no problem.