Enable two-factor authentication for web applications secured with FortiWeb

Hello All
I am looking to have Fortiweb secure all of our on-premise external web applications that require Kerberos authentication.
Also, I need to enable MFA for this authentication.
According to the Fortiweb documentation, MFA can be enabled with Fortiauthenticator, which only works with Radius authentication, not Kerberos.
Has anyone tried something similar? Can a scenario like the one below work?
Fortiweb manages Kerberos authentication and keeps the token until it requests MFA via FortiAuthenticator.
If the MFA is okay, Fortiweb should send the Kerberos token to the Web application.