You are correct that these do not translate directly with a single word. Augenweide depends on the context. If you are happy to see something we might use a phrase like "a sight for sore eyes" if you mean it to objectify someone we'd probably say something like eyecandy. Fernweh - never say itchy feet, people will take it literally and not understand what you are trying to say. We use another german loan word "It gives me Wanderlust", or would simply say something like "Seeing your vacation pictures makes me want to take a trip" Schadenfreude is another loan word English has borrowed because it makes it very fast to describe something that would take much longer in English. We would say something like "He takes pleasure in watching other people fail". If you use Schadenfreude most English speakers will know the word and what you mean.

1. Augenweide = eye candy oder a feast for the eyes. 2. Fernweh = itchy feet 3. Schadenfreude = Schadenfreude :D