We still experiencing problems with non-ASCII characters in page names.
In our case "äüö" work fine, however the trouble starts when there is an uppercase umlaut in the page name, e.g. "ÄÜÖ".
The page is created and can be display /edited.
The children macro will however produce a link which is display to an non-existing page and when selected will try to create a page by that name.