The txStatus has a couple things in it. Including an a statusCode (which if its non-zero means something went wrong) and an errorMessage (which sounds closer to what you are looking for). We get these values directly from the Access Node. Frustratingly this might not even be what you are looking for, but we definitely feel your pain, and are actively working on making this better. In the mean time statusCode and errorMessage are probably the way to go.
To keep things backwards compatible this will probably be enabled via a flag. Feel free to leave any comments or concerns in the issue, we will definitely see them.