Let's separate the definition of credit scoring from adverse action. The Beacon and FICO scores are not "demonstrabily and statistically sound, empirically derived credit scoring systems" (DSS,EDCSS) because they are not based on your empirical data. That standard is relaxing. But for Reg B purposes, you need to pass the credit score test IF the system considers age. The credit bureau scores, the developers assure us, do not consider age. Therefore you don't need to worry about meeting the Reg B definition. That eliminates your concerns about revalidation.
Adverse action reasons is a different matter entirely. You need to give the principal and specific reasons why you denied an application. Saying the customer scored low is not enough. Therefore, the reasons you give must be taken from the Beacon or FICO system if that score play a role in denial.