thank you for reporting this problem.
We need your help to track this down.
We need to track down the problem,
if this a problem in rails, or if it is a problem with Safari,
or with some machinery inbetween.
It is believed, that rails does generate valid urls.
Please give us an example of the failing url.
There is also the webserver involved.
We have to check if the generated url was wrong,
or if the webserver does not understand it.
Unicode is a tricky space.
More so with the urls.
Do not expect that a japanese String would match an url, back and forth.
This does not even work for european languages.
If you want to address some resource,
give it a integer/bigint key.
Unicode strings are not good for addressing a resource.
This will always fail, how hard you ever will try.
But you want the speaking urls?
Put it in the routes:
Just rely on the $id for resolving the request, simply ignore the unicode-tag
As an added bonus,
you might want to make sure,
the the unicode-tag is always there and is always the same,
for all the links that you show (while it is not relevant for resolving the link)
This helps a lot with google et al,
to tell them, that this is a unique resource.
Maybe speaking urls might be a thing from the past,
and we should really address resources by id only.
But it helps when reading the log files.