Take pics from much further back so we can see the whole space you are dealing with . From what I can see there is no way that stirwell can have crown molding

You're getting rid of the popcorn first right? Putting crown molding next to popcorn is like parking a Smart Car next to a Ferrari.

Also with that little 45º ceiling piece under the stairwell, if you have a very experienced crown installer there are some "unique" solutions but they will all look a bit less than ideal.

YES! popcorn belongs only in movie theatres ;)

solutions

and options are what I’m looking for.

pot lights will also be installed.

just like in the other section we already did.

Well there aren't really defined "solutions." Like I said you need someone who REALLY knows how to cut and cope crown.

So for example, crown most commonly comes in 52º, 45º or 38º varieties. If you get a 38º or 45º crown, it will probably drop faster than that stair incline. Normally you nail crown to the wall not the ceiling(especially if you have a truss roof), but in this case you could nail or glue that piece under the stairs into the ceiling, cope it into the wall on the end, and then fill in from the bottom of the crown to the stair tread with sheet rock either angled or flat. It will look a bit goofy, but if it is clean and professionally done it won't be super noticeable.

Or you could just terminate your crown in the 45º under the stairs.

Or if the stair incline is somehow exactly 45º(I doubt it) you could actually lay the crown's angled back right on that spot.

This looks like no man’s land for crown moulding... you may be able to bring some interest to these odd shape and angled walls by painting them in slightly different shades ...to accentuate them architecturally rather than with a confusing trim configurations...

I would worry about the dark gray making these areas look cave-like...and dark

This is exactly what we were going for, cave-like.

So IMO you really do not want help I think you should not have done crown anywhere .If cave s what you want you better get much better lighting and all LEDs in 4000K

what do you mean I do not want help? This is why I posted.

There is no crown moulding anywhere. So far first part of project has now LED 4,000. The other half hallway will be completed with LEDs installed.