Hi Florian!
That definitely sounds like a promising idea. You are most likely not the only one requiring consistency between storage and index data. In general, my advice is to start with a test case which explicitly addresses the situation where the primary persistence succeeds and the secondary persistence fails. From there, see what it needs to let the transaction fail. Once you have a solution for that, you can start the discussion by opening a PR. We will then see which issues could arise and try to solve them. The first prototype does not have to be perfect, a proof of concept is fine!
Best Regards,
Florian