>they seem to be resellers for DigiCert/Symantec certificates
>they should at the very least have either ETSI TSP² or WebTrust³ certifications to meet the security/trust requirements for operating a CA
A reseller does not need to meet any of these certifications. Resellers have a business relationship with a CA, and all the steps related to certificate verification and issuance are handled by that CA.
On the backend, a certificate request for your site is handled the same by the CA whether if comes through a reseller or through them directly.
>they should at the very least have either ETSI TSP² or WebTrust³ certifications to meet the security/trust requirements for operating a CA
A reseller does not need to meet any of these certifications. Resellers have a business relationship with a CA, and all the steps related to certificate verification and issuance are handled by that CA.
On the backend, a certificate request for your site is handled the same by the CA whether if comes through a reseller or through them directly.