mpdlcd.conf - how does it work ???

Volumio 1.55 is working excellent on my Raspi B+ and HiFiBerry DAC+. That done I installed a 2x16 LCD following the latest guide (updated for volumio1.55) of AndyPi which worked almost flawless. However the 2 lines of text are not very satisfying as they frequently show “unknown” and scrolling does not run smoothly either.

I had a look into mpdlcd.conf and found several entries that look promising to change. But I did not find any documentation about the usage.
Trial and error does not seem to be a good strategy to proceed, maybe a plan B or rather C at the best.

Has anybody out there some substantial information? Even bits of information are welcome.