According to the FAQs, I'm supposed to call Wolfgang Ritter, but Gabriel still refuses to call "some stranger from Germany", and Grandma doesn't recognize the name. I read the book of poetry, still no help.

Am I doing something wrong, or is there a glitch?

Nevermind, found it. Wish uhs hints was more helpful sometimes...

You know, the great thing about UHS is that it doesn't spoil everything. I assume you hadn't solved the clock puzzle?

That's correct. The problem is that the clock puzzle hint was not in the Day 4 section of the UHS hints. I was able to complete Days 1-3 without solving it, so never looked it up. Then the Day 4 hints just said "Call Wolfgang," never even bothering to reference the clock. That's bad walkthrough design IMO.

I do agree that a link back to the clock puzzle would have been good in that UHS file. Most people solve the puzzle on the first day but, when I played the game for the first time (pre-internet-walkthroughs), it took me until the third or fourth day to get all the Ritter/Knight-references and realize the "drei Drachen/three dragons" and "three snakes in a skull/dragen/snake" significance.

Still, UHS has at least a great search function.