In the first image it does look like the stock itself has some cutouts in it which could reflect a replacement of the stock. Apart from the cheek riser there is also a small slit in the stock which would enable a sling to be put through there which the regular stock doesn't have (unless you put it through the primary large opening, which isn't fully ideal).
Also in the first image interestingly we can see a handstop on the toprail just before the cutout for the gas block, which somewhat makes sense as a guide for helping users avoid accidentally grip onto the gas block. There also looks like there is a pictainny rail cover of some kind that extends all the way back to the mount for the lpvo in that image, but i'm not sure if that's just an artistic mistake or actually meant to depict something.
If they would replace the forward removable BUIS with an IR laser unit (on both the rifle and carbine versions) then you'd have a fairly optimized and modern rifle setup for the QBZ191 short of other more major modifications like replacing the gas adjustor to enable a full length top rail