There is some terminology that is getting foggy here, in the USA engine machine shop / engine build world, the terms mean:

Internal balance: The crank can be balanced with no other attached parts during the design process. The vibration damper and flywheel are neutral balanced ( no counterweights on them. ) This is the _design type_ and not the _balancing process_ or where balance holes are drilled.

External balance: There isn't enough space in the crankcase to add more weight to the crankshaft during the design process to bring the crank into balance. Weights must be added to the vibration damper and flywheel to accomplish this. This is the _design type_ and not the _balancing process_ or where balance holes are drilled.
( 360, 400 , some 440 Chrysler, 400 Chevy , 302 Ford to name a few )

Balanced assembly: The vibration damper , crank and flywheel are all bolted together and balanced. This is a must do on external balanced engines unless you allow for the missing counterweights. It is a can do on internal balanced engines. The " proper " way to do this is to balance each item by it's self then bolt together for a final check. In an production environment this added work gets expensive.

I'm guessing MB decided that the balanced assembly was a better route to go and this is sometimes incorrectly called external balance.