Do you get any autolinks at all in that post? In the same post that doesn't match Lapp & Flershem, does it match something else that might only be one word or two?
If it matches nothing at all, then it's more to do with the auto-linker not being activated. In my tests, any phrase should be matched regardless of special characters as long as it's longer than the minimum characters setting, isn't on the auto-link ignore list, isn't the name of an HTML entity, isn't part of an HTML tag or BB-Code tag, and the post containing the text uses the same character set as the article it's matching. The character set exception doesn't apply as long as the characters appear on the QWERTY keyboard.
The auto-linker won't be activated if BB-Code in general, the URL tag, or custom BB-Code isn't allowed. If the user is using the simple editor, is this because they aren't allowed to post BB-Code, or because the post is in a forum area (social groups, blog comments, etc) that might have BB-Code (or at least custom BB-Code) disabled?
Further, auto-links might not be turned on for the place the user is posting. Sometimes it might be successful in error, because the WYSIWYG editor often reports the wrong forum ID. Auto-links are activated on a per-content-type basis in VaultWiki: General Settings, and on a per-forum basis in the settings for each forum in your Forum Manager.