404 Broken link in sentence discussion
I just discovered that one can (theoretically) get to the sentence discussions via Discussion->German->Sentences then enter search terms. I looked up the sentence "Karten für drei Erwachsene und Zwei Kinder, bitte", found it, clicked on the link and landed at a 404 page. I've retried it several times with minor variations, but it's always been 404.
P.S. The problem with the translation: "Karten" can be "Speisekarten" (menus), which makes much more sense to me than the official translation of "Maps for three adults and two children, please".
I think this might have been a general problem in Duolingo a few hours ago, since I had some trouble with loading the discussion page myself (with the 404 page showing up a couple of times).
Regarding your german sentence:
The most natural translation of "Karten für drei Erwachsene und Zwei Kinder, bitte" would definitely be "Tickets for three adults and two kids, please".
"Speisekarten" would be theoretically possible, but unlikely. Why would kids get a different menu in a restaurant than the adults?
"Maps" as a translation of "Karten" in this context, however, makes even less sense to me (although - again - it would be a theoretically right translation).
I've encountered this problem too, and it's sporadic. One theory I have is that it may be a glitch that occurs only with newer / recently added discussions, and sometimes if I go back later I'm able to view the page. But there may be other things causing the glitch too.
If the DuoLingo team were running things the way I do, they would have someone monitoring 404 errors that originate from on-site links and then they'd be able to troubleshoot and fix bugs like this pretty easily without us having to even report them.
I get the sense that DuoLingo's team that programs the backend is overwhelmed and woefully unable to keep up with the basic maintenance of the site.
I just signed up for the $10/month premium subscription. Hopefully if enough people do this, they'll be able to hire more people and/or better people, and get problems like this fixed.