Torschlusspanik is the fear that time is running out for eg a career change. Weltschmerz is a deep melancholic sadness about the state of the world or life. Hopefully someone who actually speaks German can give greater nuance to those definitions and maybe some other examples.
german has a crazy big vocabulary but most words arent used and in generell the language is simplified in everyday use. for example everyone has angst but noone has bange anymore. btw good word for anxious in german.
i once also had the impression that many nuances are lost in translation but then i had to realize germans are not using all the words of the vocabulary.
Learning German is hard in the beginning, because of the more challenging grammar and "Donaudampfschifffahrtskapitaensmuetzenfabrikantengattin" but then becomes easier, as there a lot less word plays and figures of speech. It's quite regular. English is easy to get into, but to master it, you have to know them all. And the random pronunciation, of course.
Ja, Bange is uncommon. Really only used in "Da wird mir Angst und Bange!". and "Bange machen". It is still amazing to me that "Giving up the ghost" is a figure of speech in both English and German.