Folks. Timing ADVANCE is BEFORE top dead center
this equals a negative number.
your numbers are fine!
I did some more research, and in short, you are correct.
For the benefit of anyone else who comes across this thread, I will expand on this further.
In the early days of ODB2, some vehicles (most of the examples I found were Mercedes and GM) reported the timing advance data differently then what many do now. The PID that these apps use is translated as a negative number instead of a positive number. So, a -30 in my older Mercedes is similar to the 30 that I see in my newer Audi. It basically comes down to the data that the ECU is giving and how the app is reporting it.
If one is still concerned that their engine is retarding timing, a better test would be to look at the knock sensor data. If the engine is indeed massively pulling the timing, one would see a ton of readings from the knock sensor. If there is an air/fuel issue, one would probably see it in the STFT (Short Term Fuel Trim) and the LTFT (Long Term Fuel Trim). Without getting too far into the weeds on fuel trims, numbers of +/- 5 mean the engine is running great. When the numbers get higher than +/- 10 that means that the ECU is compensating for something (minor, at this point). Most cars will throw a rich/lean code when the readings are more than +/- 30.
All that being said, I will be updating my Crankshaft Position Sensor just so the ECU has good data when adjusting the timing. It has never been done in my 21 year old car, so I figure it cannot hurt. In my SLK230 (and I suspect most R170s) the timing is set based on the info that the ECU receives from the Camshaft Position Sensor and the Crankshaft Position Sensor.