I am with you, I want to listen in a lovely room, yours sounds to be so.
1. Toe-In will definitely make a difference, especially in your case, very similar to mine.
2. Tilting the speakers back will help in two ways,
a, most important, it alters the angles of reflections primary and subsequent relative to the floor, ceiling, side walls.
b. aim the tweeters so they project their narrower sound waves at seated ear height, primary listening position.
3. fabric, draperies, in the corners behind the speakers can help, any side windows that will cause early reflections
4. any large table(s), soft fabric tablecloth
5. Avoid glass on artwork on the side walls
we use tacky stuff on the bottom back corners to keep wall mounted art both level and vibration free.
6. tons of small cork/rubber/felt feet for small stuff hither and thither
You probably don't have a dining room table setup like mine, but have a peek at my setup.
My table, close your eyes, it's not there. as long as L & R get to your ears properly, your brain will make the phantom imaging which happily is excellent here.