Siemens should have experience with moving steps. If I remember correctly, moving steps are an invention by Düwag, which got assimilated by Siemens.

There are several lines in Germany which are part subway with high floor entrances, but serving some low curb or no curb stops on the way.

My personal experience was the (at the time) line 66 in Bonn (connecting Bonn with the high speed line stop in Siegburg), where the stop I had to get off for visiting my client was street level, but most other stops have high platforms.

So, Siemens should know what they are doing… and from the pictures, the design of the new vehicles is pretty simple and straightforward, which means that chances for a "Combino debacle" are quite low.