Posting Interactions (Notes, Call Transcripts, SMS Messages) to Candidates via API

We are currently working with a vendor that has traditionally used the POST recruitingUIInteractions API endpoint (/hcmRestApi/resources/11.13.18.05/recruitingUIInteractions/action/addInteraction) to push notes/candidate interactions into Oracle about candidates. We have went significant lengths to troubleshoot a bad request/400 response with no luck. We understand this endpoint is labeled as "internal use only" for Oracle, and therefore we are unable to get official support on a resolution. At this point, we are moving to next steps to find an alternative solution.

We are wondering if anyone in the community can offer help. The vendor is looking for a place in recruiting (on the candidate profile) to post notes and interactions. As suggested above, the vendor usually posts their notes under the interactions section on the Candidate profile. The notes they intend to write back into Oracle can be call records, transcripts, SMS messages, etc. They can vary in length, but can sometimes be very, very long blocks of text. So we'd need somewhere without (significant) restrictions to character/input limits. Each time the vendor posts a new note to the candidate, it