If you hate ladder work (me too) and are willing to do it yourself, look into renting a scaffold. Mine had a generous 3x4 platform for paint tray and walking room, ladder rungs with hand rails on both sides. Easy access to the top, super stable and was perfectly comfortable for hitting the high area of wall in our foyer. Stood there cutting in wall at ceiling and it was eye level, nice! Comes in pieces like a puzzle for transport, just put it together at home. I got one at our local rent-it center for abt $75 for a weekend, or $150 for a week. Way cheaper than hiring it out. Piece of cake to work from. Just wanted to offer a tip for future reference. Every time I paint something I take a fresh wooden stir stick and with a fine tip Sharpie write the manufacturer, date, room, color name/#, sheen and formula. (Abbreviated you can squeeze all that onto half the stick at the handle end, using both sides if necessary. Don't use a fat tip Sharpie, it bleeds too much and is illegible.) Then dip the stirring end of the stick in the paint can (with paint well mixed) so it's covered about half way up but doesn't cover your written info. Set it on edge of can lid with newspaper underneath to catch any drips & let it dry overnight. I keep my painted sticks loosely rubber-banded in a storage box inside the cabinet where my brushes and misc paint sundries are. Takes up little room and you have a ready reference in a case like this, just walk in the store with your stick in hand. (I've found it comes in handy too when shopping for fabrics or other items for the room, painted stick is bigger than a small paint sample and is precisely what was put on your walls.)

If there is a ridge, then you can sand it and if that doesn't work then it needs to be patched.

Clean and dull is the first step before painting anything. Wash the header with Dirtex, spackle any damaged areas, sand entire header smooth with 150 grit sanding block, vacuum away the dust, wipe with damp sponge, let it dry and repaint it. If the sanding creates any bare wood, prime with the paint, then apply two coats.

Having to look at that every day would drive me nuts. You could call the company that manages the building and ask the name of the painting company and find out from them where they get their paint - Ben Moore or otherwise. In some towns, there is one paint company that many of the contract painters use. What's the closest paint store to the building? The ceiling is probably the Ceiling White paint of the company where the paint was purchased. You might be able to remove the darker gray from the trim with some sort of paint remover like Goof Off. Failing the above, I would try to figure out what sheen of Gray Owl was used, then buy a quart and some masking tape and go to work on it. Whatever you do can't be much worse than what's there.