I bet repainted lighter walls and furniture will make them disappear.
The dark green room w white baseboards looks ok. The brown mottled accent wall in stove room and the blue carpet/shiny wallpaper room would be my first priorities to change.

It is not safe to put stuff on/over/close in front of these heaters (had a section of some synthetic curtain bleach white when the heat kicked on in my first apt).

If these are the listing pics of your new home don't worry, they always look way worse (or way better) than in-person. You will make it your own and not see the heaters behind your stuff I no time!

The green room looks so much nicer because the radiators disappear against the taller base. I'd replace the base in all the rooms with a similar base.

Unless you're in love with it, I'd replace the door casing in the rustic room, too, with white, and replace that wooden door, as well. It doesn't look like it goes with the rest of the home.