Ok so you are referring to Page 292 of this thread. Got that post about CZ BERN now.
It will help if we can all be a bit more specific with our posts.
I don’t think he is talking about compatibility issues but availability issues. What he was trying to say here was that CZ and Beretta either have their own companies making sights or some other company from their country making them so they can offer a combo. SCAR will have to loop in a third party so that might be a problem, like availability etc! However I do not agree with this either. The contract/order will be of so many sights and as it seems now, more likely to be accompanied by a ToT agreement, I do not think sourcing them will be a problem. In fact, I would even suggest that other than the three options these gun makers are going to offer as part of the deal Pakistan must look into OTHER options as well and choose the most suitable one (and I think this is what is happening as discussed in previous few posts)