At present to have custom domain names for all of the various services we have to manually create the same records and then email Zoho to activate the necessary SSL certificate.

Why not change this entire process!

My Suggestion

Radically overhaul the domain verified service, if like my organisation you have more than one business domain name change the name servers to a hosted Zoho DNS setting.

Zoho can then add in all of the various CNAME records for all of your services under the domain name. You can then activate free wildcard SSL certificates from lets encrypt.

This is a free service and will make it a lot easier to automate renewal.

You guys are great with backend code, so integrating the API won't be difficult.