“While edits made in Coda are shared with other collaborators in real-time, it can take a few seconds for them to become available via the API. You may also notice that changes made via the API, such as updating a row, are not immediate. These endpoints all return an HTTP 202 status code, instead of a standard 200, indicating that the edit has been accepted and queued for processing. This generally takes a few seconds, and the edit may fail if invalid. In the future, we may provide a way to acknowledge edits.”
This does appear to be an async issue, I got around this by adding a 3 second delay to my next call, the delay time would vary on several factors however, so not sure if there is a consistent delay that will work.