In English we almost always use "beautiful" to refer only to the way something looks. It's possible to use "beautiful" to talk about taste or other senses, but it's rare and it's usually done metaphorically or for poetic effect.
In Turkish, "güzel" seems (from what I gather from this course - I'm happy to be corrected if I'm getting this wrong!) to be used pretty regularly in situations where it doesn't refer to what something looks like.
To me (US native English speaker) "The taste of baklava is very beautiful" doesn't exactly sound wrong, but it does sound very, very odd. I think the team is right not to take it as a standard English translation of this sentence.
I think in inglish when we say Baklava tastes very good we mean in general the taste of baklava is good but in this special sentence "baklavanin tadi cok guzel " it is as though we are saying in this specific shop what is the best is thier baklava it means the taste of baklava is much better than thier other things . Yes!or No?