[roenxi]

We can't really say what is hard, because evolution tends to be more creative than anyone expects. But we can say it sounds easy - evolution would only need to come up with a "build this with reverse the chirality" mechanism and run everything through it. That'd even be what humans are doing in this research, I suspect. If there are advantages to reversing chirality then there'd be lots of paths where partially reversing chirality of parts of an organism would be interesting or creating clouds of reverse-chirality molecules would be evolutionary powerful.

It wouldn't be likely, but we're talking millions of years and a process that has overcome some remarkable engineering challenges. Finding one place where building backwards then extending that just wouldn't be such a big deal.