While this could all be stellar there are a few items I would like to suggest if you are not already doing these things.
For many core sim scenarios you have to integrate AV sensor simulation with full motion DIL in actual real-time. I am connected enough in this industry to know that is not being done by most AV makers automakers or folks selling simulation products or services. If you do not get this right you will have obvious issue which you will eventually figure out. However you will have hidden issues you will not find out until a real world problem. That will not be good in dangerous situations especially in bad weather. You will most likely not figure it out until a tragedy or several have occurred. This will happen because the sim DIL used with no motion system will not provide motion cues to the driver. That will cause them to not drive and train the AI right. Examples being loss of traction situations especially when the wheels under power slip in a straight line. Where a motion cue is expected but missing. And it situations where there is other loss of traction. If the error is not gross your system may mas the problem.(You will also have issues where people get sick that should not or the reverse. Especially passengers). In the area of proper real-time the same things will occur. Some obvious issues and some hidden. If your simulation system is sourced from your industry it is likely to be wrong. If the design includes folks from aerospace especially those who understand networked (DIS, HLA etc) simulation and simulators used at an FAA Level D level you are probably good to go. Finally I have a concern that vehicle, tire and road models are not precise enough. They seem good but really are not good enough. Especially when the roads are degraded in various ways causing traction issues. You may have to help the auto industry get this right.
Another area is that you must create a scenario matrix from the top down augmented by data from other sources including driving. It is not possible to create a full matrix otherwise. Especially if you want to make sure L4 is covered and get done in the next decade or so.