I’m going to say that I am always dubious about relying on dates in the Mirror Universe to pin down the Prime Timeline.

There seems always to be slippage or error in correspondence between the two universes, and time spent in one doesn’t necessarily map one to one to the other (transit mechanics notwithstanding).

If we take Kovich’s point that there haven’t been interactions between the Prime Universe and Georgiou’s Mirror Universe for centuries, it seems that the two universes had already diverged so profoundly by the late 24th century, that DS9 offers us some of the last crossovers.

More generally, I’m comfortable with taking Sera’s statement as an approximation of speech. She’s not Vulcan. With that, I would put T+T+T as taking place no earlier than say 2021 but unlikely later than 2030.

As for the rest, I’m comfortable with time and events being overwritten somewhat within the Prime Universe as long as the major event marker points remain effectively in place. It’s these key events, and their casual relationships that are essential to maintain - not a date.

To me, it’s much more problematic that fans (and writers) tried to retcon a disconnect between the Eugenics wars and WW3 in order to respect Roddenberry’s direction that in the TNG pilot Encounter at Farpoint, WW3 was described as being in the mid 21st century.

Likewise, moving the development of space technology back from the late 90s, especially the first FTL flight, was key to placing Warp technology post WW3, but it takes a lot of selective interpretation to discount the statements in TOS.

For those of us who were already longstanding fans when TNG premiered, these were significant inconsistencies in the sequencing and causation..

For some, it was one of the major barriers in accepting TNG a as a continuation of the same universe. While many of us, myself included, rolled with it, it wasn’t all that different than many of the criticisms of Discovery and SNW in terms of changing the timeline.

I have also taken note that tie-in author Christopher L Bennet has been pondering (over in the comments on the TOR review of this episode), that there’s been a longstanding discontinuity (or rather shift) in the timeline between TOS and TAS and TNG.

I can see why, especially as their astrophysics consultant will back up the science of it, Goldsman as TOS fan since the 60s & 70s would want to clean up the sequencing of key events over the previously established dates in order to enable fans to view the Star Trek their possible future.

My own view?

If we use the major river of time analogy for events in the Prime Universe, we could think of the version of Eugenics wars, WW3 and Warp / First Contact of TOS in the 1990s and early 21st century as a kind of oxbow, an arc now cut off, but with the bend in the river replicated slightly further down the time stream.

I also like @khaosworks@startrek.website ’s notion of a palimpsest analogy where the incursions into the time stream over write past versions but there remain artifacts of the earlier versions.