Good thoughts, but the "we have trn projects in mind for chapter 1, 2 a year, but oh yeah no scripts have been written yet" bullshit is what got us cape fatigue in the first place. Veery likely Gunn has already decided on the "role" each film must play in the meta narrative, the major setpieces have already been determined (and may even have begun to be made), and these writers are hired to try to make connective tissue between preset action and plot beats.
The first Supergirl movie won’t really connect to anything most likely. The Woman of Tomorrow comic they’re adapting is just her deep in space, she meets this alien girl who wants to hire her to help hunt down her father’s murderer and bring him to justice, and they travel throughout the galaxy encountering various obstacles while trying to find the guy. It does go into Kara’s origin and how it connects to this other girl in terms of how much their father meant to each of them, so it can work as an origin film despite it having Supergirl already have been an active hero for a while by the time the story begins.
Lanterns is the one show that does sound like it will connect to a major event, but that makes sense, they’ve said Hal and John are basically uncovering the mystery of what it is and it will be somewhat like True Detective.
I think Gunn is being careful to not go overboard in connecting things. I remember how people initially complained that Guardians 2 “didn’t advance the Infinity Stones plot”, now that’s seen as refreshing in retrospective, and Guardians 3 wasn’t really worried about being connected to the larger Phase storylines either, and again people appreciated it for that.
Like Swamp Thing will likely have a few mild continuity nods, but nothing major. Brave and the Bold will likely be focused on just Bruce, Damien and the League of Assassins, as well as beginning to set up the pre-established Batfamily (I imagine Dick Grayson/Nightwing will appear in some capacity, but characters like Jason, Tim, Barbara, etc. will be merely mentioned or alluded to for the first film). Paradise Island will likely be mostly its own thing, save for presumably setting up Diana. Booster Gold could set things up, but it could easily work as mostly stand alone as well, though I imagine the Blue Beetle(s) will appear to some degree, definitely Ted Kord as he’s Booster’s best friend in the comics, and they might have Jaime play a small role.
Also, some scripts have been done or were already being worked on when they announced a year ago the 10 projects that make up part of Chapter 1. James Gunn said he had already written all the scripts for the Creature Commandos episodes, and that he was in the process of writing Superman Legacy, and is likely finished with that one by now given it’s been over a year. So yeah, I think they’ve had plenty of time to get a good deal of scripts done.