Bruno they don't have to be triangles (I'm assuming that's what you mean by "triangulated" in order to meet the requirements. In fact sharp points are locations of stress points, so even if they were triangle shaped the points would all need to be rounded
The CFR § 393.11 isn't very clear on it, other than they need to be predictably placed, illuminate with the actuation of breaks and lenses & bulbs must meet SAE requirements for light output, shattering etc...
My guess is it's like aerospace and the medical world, these would probably work, but...
Probably not, but he can learn how to on Brilliant. And even if he doesn't watch some lectures on it, there's always hope that whoever reads this exchange learns a bit of engineering.
Bruno if you're that worried you can model it in Autodesk Fusion and then stress it.
But fun fact: plate isn't always the the strongest. Placing stratigic holes not only reduces overall weight but also allows for stressors to be placed from multiple forces and directions.