It seems like you've already proved your conclusion false though if you ended up using an HTTP server anyway. The conclusion seems to be that Flask wasn't suitable for the task.
You are right, the conclusion should be revised to: "I ended up using an HTTP server anyway, but I choosed the more efficient one", because Flask's http server is for testing only. Sorry for the unclear. I think using a Unix Socket could be more efficient but I don't want to be over-engineering :)