Any battery can leak, I had a At-AT from the 90's still in the box that has batteries leak and another toy from 90's in the box that batteries just dies. There seems to be no rhyme or reason why one battery leaks and another doesn'tSo if a battery dies or drains on you first, is there still a chance of it leaking? Because I've had lots of dead batteries in my time, but hardly any actual leak that I can remember (other than in some of my old toys from the 80s perhaps).
In any case, I am tempted to put some kind of red or blue gel in R2's eye, so he can still look like he's actually "awake" on my shelf even when the lights aren't activated.