With the friendly help of Lunaman06 from GS forum, I was able to solve my problem. At least partially. The solution was not really trivial and I would never have managed it without his support. Here are some details.
However, I finally can switch to the desired Seqtrak preset from my DT. I created a PDF with all the BNK, SBNK and PROG values for every AWM2/DX synth preset of the Seqtrak:
DT2SEQTRAK.pdf (205.4 KB)
To be able to use this table, you need to know that Seqtrak only reacts to program changes if the SBNK value is also changed afterwards. This also applies if the correct SBNK value is already set and only the PROG value is changed. In other words: The Seqtrak only reacts to program changes if the SBNK value is also changed.
I don’t know why the Seqtrak is behaving so strangely. Due to this restriction, it is unfortunately not possible to navigate through the Seqtrak presets using the DT’s PROG knob in the SRC page. If I place a lock trig on the last step of a pattern to temporarily change the SBNK value, the sound will be cutted off. This is because the Seqtrak reacts immediately when the SBNK value is changed … quite the opposite if I only change the PC value. I don’t understand this, but I’ll have to live with it.