I like celery girl's rug which has some warm colors which could be repeated in some of the pillows. The room immediately looks more interesting and warmer with this rug. Drapes in an oatmeal or cream color might also help, along with more art on the walls. It's a very nice room to begin with and with the rug and some small changes could be gorgeous. I don't think the ottoman is too large but it does have a heavy presence that a glass/metal coffee table would not, and it would make the room look larger and more airy.

I feel like I want to 'push' your furniture back a bit. It's like you're trying to fit everything on the rug and it looks squished. give everything some breathing room. you've got some beautiful pieces in there. very nice room. the color opposite gold/mustard on the wheel is purple. I think any tones of purple, aubergine, violet, would look very nice and compliment what you have. as for the wall above the bench, something like this artwork would be a nice addition: https://www.overstock.com/Home-Garden/Blissliving-Home-Aya-Purple-and-Metallic-Print-Cotton-Decorative-Pillow/14193588/product.html?TID=QV2:VIEWALLDETAILS

I’m curious, though: if picking the right color based on window or light orientation isn’t a sound strategy, why are there so many articles about it? Because it's lucrative. It depends on what you mean by "articles". There are scientific studies and white papers about azimuth, fenestration, cardinal and intermediate geographical directions and how daylight propagates through interior spaces. Also, lots of good stuff about how the eye adapts to light and dark illuminantion. If you're talking about posts on blogs, most of them are garbage. It's a lot of baseless, subjective opinion presented as expertise. Bloggers know they can make up whatever they want about color and no one is going to call them out on the bulls@t they publish - because there aren't that many legit color experts reading the crap they publish to call them out - or care. Most people have not one fat clue how color works but are intrigued, fascinated, sometimes romanced by color. Which makes it a hot topic and how color responds to NSEW light is Google keywords rich. So, whatever "systems" and "rules" bloggers want to make up, and sometimes slap a price tag on, innocent people who don't know any better are willing to gobble it up and adopt their color point of view as if it were gospel without question or vetting. Blogosphere is at best reductive when it comes to how color works and it's the last place anyone should look for information. The damage it's done to color literacy is actually quite sad.

I am interested to find a way forward with cyan, purple and yellow! What a challenge. I have teen boys too. Some boys care a lot about how their room looks, some boys don't care at all---I have both in my house, ha. First of all, you need to add to this thread a room layout. That will help. Next, with those colors, I would think in terms of a yellow comforter, cyan (bright blue, right?) colored sheets, maybe, and a little dash of purple here and there. Maybe some art or a wall hanging/tapestry (or a rug) with those colors can give you something to pull colors from. You haven't mentioned a budget?