Alright, so I just gonna go on a little rant here.
It seems like they just wanted to have an excuse to put Earth as part of the PSO2 story, It's done just so terrible.
The episode 4 story feels so forced, I just dont know how to explain it where to begin. It feels disconnected from the main PSO2 lore about ARK's versus Dark falz/Falspawn and profound darkness, and they used that terrible Sword art Online sub-plot to make that connection between Earth and Ark's, which honestly just adds nothing to the PSO2 lore at all.
Beside that, one thing that annoyied me the most in episdoe 4 lore was pretty much those two, most regular looking school girls (Which are Hitsugi and Kohri) that suddenly pull out that deus ex-machinima bullshit and suddenly turn into warriors from the Japanese and Nordic myths, get a much better and cooler looking katana than mine, and save the day, It's just so pure bullshit I just can't. The entire episode 4 pretty much seems to revolve around those 2 school girl chicks and mother corps, where Arks are now nothing more but for a side-plot and my character is now some sort of sidekick filler, irrelevant to the story just so I will able to fight Phantasm Mobs.
I think the thing that annoyed me the most was the releationship between Hitsugi and Kohri, it is absolutely terribly unrealistic and poorly written. They made Kohri a generic edgy yandere character, while Hitsugi is your mary-sue, aka a female version of Kirito, not to mention the releationship between those 2 chicks is just borderline yuri romance.
If you want my opinion, I honestly think Episode 4 more as a fanfiction made by an edgy 16 years old white bisexual girl, like the lore and character writing in episode 4 is so bad it just perfectly reflects on this joke assumption.