Thanks Jozko,
This command perfectly lists the CA details, not though the certificate(s) generated -and assigned to a particular gateway- by this CA itself.
I've tried another flavor of it: fwm printcert -obj <gateway>-cert <cert nickname> but didn't list the details we're after, rather it listed the certificate generated by the internal CA. Adding or removing the -cert option didn't make any difference in our case
Wish this command got an option as below:
fwm printcert -ca <3rd party CA> -cert <cert nickname>
But I still think, if the GUI can list the details, then there should be a CLI command to do it as well... I'm still digging 😉