Well, canoo.net explains verb tense sequence.
Nothing specific for nachdem is mentioned, but I remember from a German course that nachdem is different with respect to other temporal conjunctions. Can you help please?
I cite the page you have linked:
Unlike some other languages, German does not have strict rules for the sequence of tenses.
That's true. Though that page lists some obvious examples in its Anteriority section which indeed have a tense sequence. But I show you a counter example:
Ich sehe es mir an, nachdem ich hiermit fertig bin.
Ich sah es mir an, nachdem ich damit fertig war.
This is both present/simple past tense. But the sequence of events is pretty much clear: first the completion of the current task, then looking at the new stuff.
Why is this possible? Because present tense is not only describing the present but also describing the future in German. And past tense does this, too, for narration. The sequence of events is put only by nachdem. Future, nachdem present.
So German does not impose a tense sequence on you. Not even with nachdem.