This is a failing of the veriloga model you're using and the BSIM4 manual. If you look at the code from the bsim site:
It contains a definition of these parameters. So they're in the BSIM groups source code...
There are potentialy a few deviations from the official code, usually to add some additional features requested by specific customers (primarily a certain large foundry), but those wouldn't alter the default behaviour of the model unless those specific parameters/values were used ("spectre -h bsim4" lists these and makes it fairly clear they are specific to a particular foundry). But overall, there should be very good correlation with the BSIM group's code.