> please any hint on how to "manually" remove those two failing services?

You should do something along the lines of the following:

(remove (lambda (service)
          (let ((type (service-type-name (service-kind service))))
            (or (eq? type 'mingetty)
                (eq? type 'console-fonts))))
        %base-services)

Notice the function call to service-type-name.