It looks like some custom CSS code on your web page which handles the right-to-left aspect of your web page is switching the left and right hit-areas of the gallery.
I suspect it is the following code from your 'rtl.css' file (specifically the 'direction' property).

#page {
    text-align: right;
    direction: rtl;
}

This code sets the direction for everything within the #page container including your Juicebox gallery (which is nested within the #page container).
You could either modify your CSS so that it applies to only those elements on your web page which require the 'direction' property (through use of further CSS selectors) or you could explicitly set direction: rtl; for the Juicebox gallery container by editing the WP-Juicebox plugin's 'wp-juicebox.php' file in a plain text editor and changing line 287 from:

$string_builder .= '<div id="juicebox-container-' . $clean_gallery_id . '"></div>' . PHP_EOL;

... to:

$string_builder .= '<div id="juicebox-container-' . $clean_gallery_id . '" style="direction: ltr;"></div>' . PHP_EOL;

Please note that the line number above refers to the current version of WP-Juicebox (v1.4.4.1).

Instead of my original suggestion above, try adding the following to any of your CSS files:

.jcbx-glry-classic {
    direction: ltr;
}

This should hopefully work for both normal and fullscreen modes.

I have logged this issue as a bug with the developers and it should hopefully be fixed in a future version of Juicebox.
Thank you for reporting it.

You're welcome! I'm glad my suggestion worked.
(Hopefully this should only be a temporary measure until the bug is fixed although it will do no harm to leave the CSS code in place.)