Why do the CRJ700 window shades open in different directions?
Judging by an exit photo here, you're right.

When there is an opening in the fuselage (e.g., where the emergency hatch would go) the surrounding area needs extra strengthening. Below is a high-res example for an Airbus fuselage:


(source) Notice the extra and deeper stringers to the left of the door, and the lack thereof away from the door where the windows would be (yet to be cutout, but you can make out one).


(gettyimages.com) And here's a CRJ700 fuselage (first fuselage actually).

While that's the front service door, not the overwing exit, note the white stringer above the first window to the right. Its depth is clearer on its mirror on the left by the shadow it casts.$^a$

And since a sliding hard blind needs to go somewhere, they typically go into a hidden tray, which takes space. Here is an example from a McDonnell Douglas patent from the 70s.

An upside down unit flanking a hatch could very well be installed that way to make way for a structural element, or to make way for cables/pipes/tubes in the area, especially that the CRJ700 is a narrow plane.



$^a$: It won't affect the first row seats though. Note that the passenger entry door (port side) is taller, so the topmost stringer is already well above the windows. As for the right side, depending on the configuration this area will have either a galley or a lavatory. I tried to check for photos from inside the lavatory, but it didn't have a window (on the outside, the window is there, it's just blocked by the interior panels from the inside – photo below).


(thepointsguy.com)