Static problems with wall construction

Hello,

I have a problem with my structural analysis. We are building a single-family house with calcium silicate stones. In the upper floor, the structural engineer specified that 2 walls must be made of drywall. That is out of the question for me. My question to you: Is there an alternative to drywall? I was perhaps thinking of Ytong stones. Does a wall made of Ytong stones weigh more than a drywall wall? Are there any other alternatives to drywall that you could suggest?

Since I have no knowledge of structural analysis, I naturally don't understand the engineer's calculation. If necessary, I can upload it again here.

Regards

Why no drywall? Because of sound insulation? Then Ytong is not the be-all and end-all either.

What stops you from asking the structural engineer why it doesn't work with KS and what needs to be changed to make it work?

Yes, I will probably have to do that. I just wanted to gather ideas and tips here first.

Drywall construction is not the worst alternative.

In statics, it is often referred to as "lightweight construction." This also includes other types of walls besides drywall. This can often also be Ytong or KS in a lower density class. However, I would always prefer an insulated drywall to 11.5 cm thick Ytong ...

Wooden stand is not too heavy either.
Which requirement contradicts drywall?