Yes, even though they're mounted on the back wall, they're still side surrounds and should be positioned as far to the side of the listening position as possible.

When facing forward toward the TV the inboard tweeter is aimed more or less directly at the listening position, while the outboard tweeter bounces off the nearby side wall, to good effect. Incidentally, judging from your diagram, a sidewall mounting about 6" from the back wall is feasible and should be similarly good.

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Enjoy the music, not the equipment.