I was fooling around yesterday evening with the Language Reference and found that if I press ctrl-alt-left arrow (and none of the two fields have the focus), the Language Reference window goes left by one step (displays the previously seen page). Same happens with the right Key.
Now, I got a beep in the process, but just because I was watching TV (and so the sound was ON).
Of course, I prefer the classican cmd-left arrow or cmd-right arrow, but better this than nothing !
2015r1 on Yosemite 10.10.5 (with the last updates), MacBook Pro 2014-12.