I like the window treatments and wallpaper, but there is way too much black overall here. I'd start with the nightstands -- replace with something lighter and nonmatching, ideally, or just remove the mirror in favor of some art, and add light (matching) lamps on each side. Agree that the country flowers seem out of place -- maybe find something solid or otherwise more in keeping with the simple elegance of the rest of the room... Also, if you don't love your headboard, you could consider adding a tufted bench at the foot, which would hide part of the dark frame, tie in with the wallpaper, and give you someplace to sit! :)

I think that your suggestion to replace the comforter/duvet is correct. That (at least in the photo on my monitor) comforter looks to be not in harmony with the other things you have. I think a light solid or tone on tone duvet would be lovely. I think the feature wall wallpaper and everything else work together. I do like those lamps suggested above as well.

It might be possible to recover the headboard (not the sides). I made essentially a giant sock for ours (run fabric lengthwise and sew ends, pull over existing headboard)...or if you can access the back, fabric could be stretched and stapled to the back. That may give more options. The sides would still show, but may be less noticeable and help break up the expanse of black.

IMO since you have the black headboard why not do more black and silver theme. Take the valances off and dye the drapes gray

Yes, to your questions ... change lamps, bedding. Those will really freshen it up. I’d remove the valances and just have panels.

Maybe add a rug for a nice, layered, textured look:

I love accent pillows like this Ikat style:

This is space during the day. No duvet to see what the white looks Like. Just grabbed a lamp from another room to see what the silver base looked like.

This picture, pulled the mirror

Covering the headboard would be easy and so would covering the sides. I would remove the valences as they are so heavy looking. The mirror would look better hung to match the height of the window. Center the bed between window and mirror.

or you could use a throw, quilt, rug or tapestry over the head board to add color/texture and break up the black.

I think it looks so good with the small tweaks (the white and the silver lamp).. I am not so bothered by the black headboard.

When looking for a duvet, should I be looking for colours to tie into the drapes or the feature wall?