Ceiling – Should I prime just repaired areas or the entire ceiling before painting

Priming then painting: The texture is water based, so you need to prime first with oil or shellac based primer. This will seal the texture and "waterproof" it.

Use plenty of ventilation and possibly an organic respirator.

Once primed, any paint can be used (make sure the full drying interval is used).

Removing: will work before any painting. Put down waterproof tarp, wall-to-wall and taped 6" up. Use a misting hand sprayer or a garden sprayer. Let soak 15 min, respraying if dry spots develop. Scrape with a long handled pole and a stiff angled putty knife. Keep the knife flat and start slowly until you get a rhythm. No sense in making another repair for gouges. Clean any residue with a new sponge mop and some TSP or a light detergent.

If it was indeed just recent & not an ongoing for years situation. Then, let it dry for a week or 2 & see how solid it is then. As long as it feels as solid as before & the rest of the walls, then definitely scrape off what bubbled, split & wrinkled paint you can so there are no lifting or flapping edges.

You'll want to fill those new low spots with Joint Compound or Spackle for a nothing ever happened end result. Lay that on in very-very thin coats just as thick as the paint you have surrounding the scraped areas. Dry-Sand with sandpaper to perfection & a lot of dust or Wet-Sand with a wet sponge for no dust. Let dry & do another Compound or Spackle coat, if needed & sand again.

Then, roller-on a Stain Blocking Primer & let that cure for 2-days, you shouldn't need a 2nd coat but do that if it's needed. And finally, roller-on your paint, 2-coats over the primer-ed areas & even do the rest of both walls to get everything uniform & to use up your paint...of course do this with the Primer too, prior to the paint, in order to use that up as well.