I started doing jujitsu a few months ago. The title of the article and this top comment had me bewildered until I remembered what jujitsu was in this space LOL
The first part is correct, which is why during recovery transactions need to exist in both places to be applied else they are discarded (from either). If it works as stated on paper then it would give the C for consistency in recovery but of course fails at durability.
Reading through the article it’s explained in the recovery process. He reads the intent log entries and the completion entries and only applies them if they both exist.
So there is no guarantee that operations are committed by virtue of not being acknowledged to the application (asynchronous) the recovery replay will be consistent.
I could see it would be problematic for any data where the order of operations is important, but that’s the trade off for performance. This does seem to be an improvement to ensure asynchronous IO will always result in a consistent recovery.