It's very difficult to get paint "perfectly smooth"....and it's not done by applying 3 quarts in just 5 coats.
What happened to applying all the Coats as "Dusters"? Did you read any other member's attempts? I don't recall any missive from you asking for spraying advice. But then again...to many this spraying business can seem quite the no-brainer. On the other hand...some are abjectly terrified of attempting the chore without considerable "hand Holding". I actually don't mind that...as few who require such have issues when the supplied correct procedure is followed explicitly.
You don't mention how long you waited between coats either. All in all it does not appear to be bad....of course I do not know if the shown example is indicative of the entire surface.
Sometimes, it's simply the eyes involved. Either the viewer is sitting jammed up close to the screen and can resolve the texture...or they have Lasik-quality vision and can spot the hair a frog from 15'. Those types find it hard to get satisfaction from almost any screen. But brook no doubt....a virtually smooth surface can be had by spraying.....but you simply must do it as instructed....especially if your using the larger 2.0 needle that come standard on the Graco. Just enough others have mentioned that they tend to get Orange Peel to have made me start recommending that the purchase of a 1.5 mm needle assembly is essential to help ward off such issues. The finer spray goes far in that regard, but even so, improper use (wrongful spray technique) can still lead to less than desirable results...if indeed not disastrous ones.
Anywhoo....you can sand down the small amount of texture I can see easily enough. But to me it does not look nearly as bad as "Orange Peel". Using a Large Fine Grit Sanding Sponge 3" x 1" x 8" (Home Depot / Drywall Tools Dept) and sweeping the screen lightly will remove the surface irregularities, but you have to do a very even sanding job. The Fine Grit sponge should not "scratch or gouge" the surface....but the entire surface must be sanded equally or any are that still has any coarseness with stand out under projected light.
As to if your end results can stand up under visual scrutiny, I cannot say, let alone assure you. But You do have all the "Good Luck" I can send your way at this point.