First of all, we know that the intelligent lighting system in the U.S. is neutered due to regulations comparing to the rest of the world...

My question is more specifically about the adaptive high-beam assist (AHA) in the US. Note that the manual doesn't talk about fancy lighting patterns, so it would seem to be indeed specifically written for the US market.

According to the US version of manual under AHA:
Part 1: "If you are driving at speeds above approximately 16 mph (25 km/h): The headlamp range is set automatically depending on the distance between the vehicle and other road users."

Part 2: "If you are driving at speeds above approximately 19 mph (30 km/h) and no other road users have been detected: The high-beam headlamps are switched on automatically. The indicator lamp in the instrument cluster also lights up."

Does that mean when the high beam is not on (part 1) but AHA is on, the low beam at least tries to go as far as possible but stops as it reaches the vehicle in the front?

This is on page 121 of the manual for C-Class 2016 PDF manual.

Any definitive insights would be great! Thanks.

 

Your assumption is correct.