my accent is not so good (what rhymes with orange?)

Pale pink or peach

Along the Moroccan theme, you could go for a pale terracotta-ish yellow?

I think neutral brown earth tones. I would paint the other walls off-white or a light beige/sand color. The accent wall is supposed to stand out so the other walls should be muted. Or go the opposite direction and make the room a Latin American-inspired color explosion. Bright oranges, greens, reds, etc. can make a place feel really bright and festive!

I'd go with a lighter, less saturated orange. Bring in some pale green textiles like blankets and pillows (curtains?) to keep it from being overly hot but still warm. With the darker purple accent (maybe get a purple lamp or some art, too) you'll have a pretty balanced triadic color scheme that will support the red couch.

You could always put in a chair rail and paint the upper or lower half another color, if that's just too much orange. I think if you're going to have brown-black wood, gray will look weird. I think the yellow or blue suggestions are better, as both look good with brown.

For what it's worth, Dr. Seuss art often pairs a similar share of orange along with light or medium blue to good effect, and if it's a kid's room, that might not be a bad look to aim for. Examples http://imgc.allpostersimages.com/images/P-473-488-90/76/7642/TA8G300Z/posters/theodor-dr-seuss-geisel-one-fish-two-fish-collection-iv-blue-fish-orange.jpg and https://www.bibdsl.co.uk/imagegallery2/bds/201213/9780007455942.JPG.

Cream/off-white (ivory, even) or a light, warm, yellow-beige for the other walls, with robin's egg blue or turquoise accents.

http://www.apartmenttherapy.com/pegboard-in-kids-rooms-207236 and looks like a fairly cheap and most importantly useful way to set up a big storage system that can be styled well (add some http://thisisourbliss.com/2014/08/26/nursery-project-pegboard-gallery-wall/, some art prints and toys here and there, spray paint it a great neutral) and that would turn your orange wall into a bright frame for a big feature in your room.

Hi there. My son's room has an orange accent wall. The orange color is Benjamin Moore http://www.benjaminmoore.com/en-us/paint-color/sharpcheddar and the other three walls are also BM, but the color is gray, specifically http://www.benjaminmoore.com/en-us/paint-color/bunnygray. Other colors in his room are turquoise (on the rocking chair) and chocolate brown (some pictures on the wall featuring owls). In our home, we have lots of colors everywhere. Both my spouse and I gravitate to bright colors and vibrant patterns, which we know are not for everyone. But we like it, and our son likes his orange wall, which he calls his "mac and cheese" wall. YMMV. I support your orange wall!