For those still looking - Scion has a good mix of Scandi wallpapers https://www.wallpaperstudio.com.au/brand/scion

I would definitely paint out timber frames, they in themselves become the feature if you don't…..and I would hope you mean a soft grey! To "hide" skirts and arc's (I renovate and sell for a living) I do them the same colour as the walls but in a satin finish…..you could do semi gloss….a water based enamel works best. Make sure you prep them well though, either a good sand to rough up, or something like ESP. I always thought rule of thumb for a feature wall, paper or paint, is the wall opposite the greatest light source, ie. the wall that gets hit with the most natural light. Failing that, I think it would look lovely on the alcove/bay window wall and do the inset of the alcove/bay window in a contrast….say a soft version of the pinkish hues in the paper??? You seem to have some substantial pieces of furniture, and a piano, so doing the other walls would compete and look overbearing to me. Unless you are going the whole Regency style embossed paper/stripes/pattern everywhere…………...

Ok, the shop I'm referring to is called WallCandy & they have a branch in Sydney. Here are the details: Address:2 Danks Street, Waterloo 2017 Phone:(02) 9331 5884 Email:sydney@wallcandywallpaper.com.au

I'd search Designers Guild. Or Porters Paints. But others will be along with ideas.