If you have this setting set to CA when you do the import PWM will import the root CA cert instead of the endpoint cert, and use the CA cert for validation. As long as they keep the CA this should work at the expense of degraded security.
Settings ⇨ Security ⇨ Application Security ⇨ Certificate Validation Mode
If you have an older (version and you should definitely not be running anything but the latest in production) or started the config in an older version the default is not CA.