While the "no code required" thing is novel in your case (you've built a UI that is essentially database/CRUD-L with views), it's insufficient for the sheer number of changes we need to make. Making changes via the UI, by hand, is slow and error-prone, and will take a lot of time. There is no way to programmatically verify the integrity/consistency of the changes we need to make, and this is troublesome from the "reduction of toil" principle of Site Reliability Engineering.
Ideally, not only would this be a fully-supported API that is exposed to the public, but you would also provide a first-party Terraform provider so that I can commit all schema/config changes as code into Git (or whatever my SCM is). This would empower us to follow our guiding principle "automate by default". This would not only make people like me more efficient, but it would also make your internal customization teams more efficient — which, I assume every company wants. (Yes, I understand that you bill hourly for customization as a value-add to your core platform.)
This is quite the bait-and-switch from having a "user-facing API" that my sales team was looking forward to. Can you speak publicly about any such API/tooling on the horizon?