Minor quibble (but then what other kind of quibble would it be):

In DS9: “The Adversary” the leader of the Breen Confederacy in the 24th Century is known as the “Autarch”.

Actually, "autarch" was the title of the Tzenkethi political leader, not that of the Breen. To my knowledge, the title of the head of state of the Breen Confederacy was never spoken (except perhaps in the form of Breen static).

Loved it.

Some amusing details:

• For Pike's singing voice, he adopts a kind of Meatloaf/Russell-Crowe-in-Les-Miz style that is exactly the right mixture of masculine and adorable.
• The build up to the Klingon Boy Band: We know that Klingons love opera, heightened emotions, spontaneous group singing, and choreography (if you're willing to consider martial arts a form of choreography). La'an even explicitly mentions singing old sea shanties which would seem to be an obvious way to translate the Klingons into musical form. So naturally, I was shocked that the Klingons would not immediately assimilate into their new musical reality. I even told my husband, "I can't believe the Klingons would want this to stop!" And when it hit, everything made perfect sense.

David wasn’t aware that Kirk was his father

Technically, David did know that his father was an "overgrown boy scout" named Jim Kirk, but they had never met before and evidently knew little about one another aside from their mutual existence.

I take your point about wanting a more cohesive narrative, but I think there is a more important function served by the idea of shifting timelines. By allowing for the same essential historical events to occur just in different years, Star Trek can preserve what I think is one of its essential conceits: that it depicts our future.

I think the world of Star Trek was and is meant to be understood as a view into how we could develop, as a goal that we could achieve. Certainly, as a kid, that was why I found it so compelling. It showed me the great things that humanity could achieve if we decided to listen to and trust one another. It showed (admittedly not always very well!) that everyone has a place in the future, even people who are might currently feel hopeless, left out, or oppressed. While I can only speak for myself, I never felt that sense of purpose from other major sci-fi or fantasy stories. I may enjoy Star Wars or LotR, for example, but they don't mean as much to me because I don't feel like I or the humanity I know have a place in those worlds. They depict the dead past of a distant place rather than a living future that we could all have a hand in shaping.

I say that knowing that Star Trek is essentially fantasy, of course. My point is that, my maintaining the illusion that we are living in Star Trek's actual past, it makes us feel connected and invested in a way that is different from how we might connect with other stories. I don't know if that's the reason for introducing the concept of shifting timelines, but I think it still makes it worthwhile just the same.

Just here to note two details I appreciated:

1. La'an still doesn't know what a Romulan looks like after her adventure. The only one she met was surgically altered to look human, although Sera did drop a hint by complaining about the ears. Still, there's plenty of aliens with non-human ears, so not really much to go on.
2. If she was paying attention, though, La'an did get another clue about Romulan physiology: When she shot Sera, the blood spray was green! Of course, Sera remembered her grandma's old recipe for molecular solvent, so La'an may have thought that was the reason for the coloration.