If he discovers the anomoly, on the other hand, the applicant would
be expected to take remedial action as soon as it was discovered,
i.e., change the frequency back to the proper one...

But what you are missing, I thnk, is that there is no provision for
testing the applicant's ability to perform procedures with less than
all equipment on board, except for failing the "primary instruments".
i.e., AI and DG, or the equivalent on a glass panel, and simulating
loss of communication equipment. There is no task set up to fly
procedures with failed navigational equipment.

Perhaps I am missing that, but that's not quite my issue (which is more
of a puzzled question). In the case of "failing the engine", the
examiner typically pulls the power lever back and says "your engine
failed". The equivalent response seems to be to smack him one, put the
power lever back, and say "no it didn't". Does the PTS in fact say that
the examiner may play with the power lever?

In an exam, there's a certain amount of make-believe problem that is
accepted for the purpose of showing that one can deal successfully with
a real problem.

Jose
--
Get high on gasoline: fly an airplane.
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