Testicles are actually incredibly durable. I remember reading a paper that discussed the results of torture on POWs during the Vietnam War. Turns out electrical shocks do not harm the testicles at all, and they can survive a fairly nasty beating without any lasting harm.
Rupturing a testicle really depends on bad luck. And even a ruptured testicle can be salvaged in most cases. Even if you completely lose one testicle, there won’t be any significant changes as the second testicle will be able to handle producing the sPerm and testosterone.
Basically, a kick to the halls hurts but doesn’t do permanent damage.