I fixed the url generation for each page node by doing url-encoding of each path component with ISO-8859-1 encoding.
I haven't tested with site manager yet because it has been refactored a lot with Wicket.
However, when I add a page with a name containing diacritic character such as ó, it works fine.
By the way, if I create a page in the page customizer with the same name, the page is actually created by another styled name.
For example, if I put 'helloó.psml', then the physical file is saved as 'hello_C3_B3.psml'. In this case, there's no problem with the customizer.
It is a nice feature because it provides more safe page file generation.
Anyway, if a page is manually created with diacritic characters, then it can be served correctly now by proper url encoding.
By the way, I think that the portal site manager should work as same as the page customizer.