It sort of seems to me that Heroku stopped development / experiments after getting a bunch of traction. They were spot on solving a specific problem, early, and as time went on, said problem became a non-issue?
While all of the answers are valid, another option that I don't see here is n8n. I used it for something very similar to your requirement and was able to run it for years without intervention.
I see this as a win for accessibility, and a way to standardize many complex problems under the same umbrella. Would be interesting to find if they'd publish this, and it could lead to a way to fast-test the UX of many design iterations.
Currently, that process is slow, expensive and requires too many people involved to design, process and review the data.