Last modified: 2014-11-07 12:53:20 UTC
Please have a look at https://www.wikidata.org/wiki/MediaWiki:Gadget-rightsfilter/hu where the link has the form [[:hu:Reguláris kifejezés|regex]]alapú and "ú" is not linked. This is a multilingual project, so all letters should be included into links, or at least all Hungarian letters. :-)
This is link trails and it is part of the localization that would be very difficult to get right for everyone. In this case I would say put what you want to use for the page part into the link and do not depend on the link trails.
It could also be that the content language is still English in some cases, but it doesn't seems so form the content source.