Well, what is suboptimal... One would engineer it differently, it makes a weird, seemingly unnecessary, loop around some other tracts. However, being a biologist I can also imagine that if we'd reroute the thing in someone using surgery, that person suddenly gets more infections because bacteria find their way up the tract more easily (no idea, but could be!). The point is... It's a mess based on some earlier mess, but it works, and changing one part in this mess can lead to unpredictable results.

As for "discontinuous evolution"... Again, what is discontinuous? I'm sure there are events to be found of which the probability of them occurring is so small and the effects so large that they'd fall into someone's definition of "discontinuous". But I think there is by definition no such thing as discontinuous evolution. If it occurred, it had a non-0 probability of occurring, then again, maybe the universe is infinite and everything has a non-zero probability of occurring. This is getting philosophical haha. Maybe listen to some Mindscape podcasts (Sean Caroll).

Actually rabbits eat their excrement again. That's also probably not how an engineer would make it (or an intelligent designer would design it, since we seems to be going in that direction ;) ).