The graph of the maximum radiation in the Radiation chart of the met component is often too low. I don't know what method is used to make this estimate. Maybe the clear sky transmissivity is incorrect? Anyway, I don't see how a generic set of parameters for the method can be appropriate for all sites around the world.
The issue is that some users will look at the radiation chart and think the observed radiation is way too high because the maximum shown is much too low.
Don't know the resolution to this.