While I generally agree on the "Don't" approach (to make one's life simple) the fact is that I am migrating to my server several customers' sites that were already written in that way, (thing like IMG SRC="école.jpg").
I.e., someteimes one cannot take the simpler road.
That said, I suggest a small experiment...
go to the main russian wikipedia page ( ru.wikipedia.org )
You'll get redirected to a page with a Cyrillic URL, like all pages of ru.wikipedia.
If you copy the URL in a notepad, you'll get the form that was actually requested to the server:
That is, UTF-8 characters have been percent-encoded, as specified in RFC 3986
This URL can safely travel through proxies, through Google translate, etc. etc.
So, what is good for wikipedia can be good for my sites :-)
If only I was able to configure apache...
The odd thing is, other apache installations behave as expected (use UTF-8 for escape-encoding), I just cannot find the way to set the url decoding on cpanel servers.