Currently, CHR key is not handled by the XKB, but by something else (probably hildon-input-something).

See in

http://my.arava.co.il/~matan/770/rx-44-he

For an example of changing this situation - CHR becomes a normal modifier key, with shift+CHR used as CHR lock. This cancels CHR's special meaning, so if you use something like this, make sure you put all symbols you need in the key map.