Its about 50k, yeah

The Equestrians and AIF have the same doctrine because of divine intervention stuff

The Collective merely dropped part of the tittle in regards to name changing, they have the same doctrine because its the literal center piece of their culture, and as such they cemented it through somewhat distasteful means. I'm not sure what you mean by appearance, but it has changed, their ships are less ornate and bear less physics identifiers, their structures are much, much less on the pretty side (which is saying something, as they weren't attractive back then) and have mostly become cold, dull and comfortless. Politically, they are grudgingly accepting help for pretty much the first time ever, are much more on edge and have much less time to deal with anything, preferring quick and direct talks over meetings

The Hach were completely absorbed by another race, so they've obviously changed a lot

Not sure with the Sazkarjhit

Pretty odd how accurate all these supposed myths are though, maybe we need to throw a couple in that are completely off the mark to save some face xD