Well...it's a little late in the game to make color and/or pattern suggestions. But you did ask.
Wasted your time? That's a bit harsh. Overkill in one direction? Absolutely.
The Triangle extends about 2x as deep into the room as it needs to. You would have benefited more from a wider Base over the Screen Wall...perhaps a layout starting at each corner that extended out perhaps 6' at most toward Ceiling Center, encompassing the 1st 2 rows of Cans. Painting out the Screen wall around the Screen does nothing to improve the Screen's performance or how the Screen's light affects it, but it does help blend and compliment the surrounding darker areas. It is more a cosmetic consideration than anything else.
Design-wise,angular geometric designs on a Ceiling are best complimented with similar corresponding vertical(diagonal) intersecting lines on the Side Walls. The Ceiling area being the most important (...you nailed that...) so the coverage on Side Walls that are as far away as yours can extend a minimal distance.
Doing as large as painted Wall Screens as I normally do, mostly I can convince a Owner of the merits of at least painting out the Ceiling in a mid-toned Grey, and the side walls in a slightly lighter shade of the same Grey. Anything but White. White requires that one either accept the deleterious effects it creates, or measures like the illustration below must be considered.
Actually, many find the geometric "look" pleasing, and the encapsulation of the Screen area wholly appropriate. Your extended Triangle seems to represent more of a design meant to mimic the dispersion cone of light emanating from the PJ's Lens. I don't dispute that it drastically affects the aesthetic of the room in general.
But....and however........T'is better than nuthin'.
I would chop off the depth by 50% though, and widen the outside corners. You can at least do that with a minimum of fuss and bother.