Here are some suggestions from me as a native German guy with lots of GUI design experience:
Portfolio Tab:
Replace "n Assets" by "n Vermögenswerte".
Replace "Claim your rewards" by "Belohnung einfordern", or "Lohn einfordern" (if too long).
DEX Tab:
Replace "transaction fee" by "Transaktionsgebühr".
Replace "trading fee" by "Handelsgebühr".
Replace the big "HANDEL" button (to start the trade) by "Ausführen". Because "(der) Handel" means "(the) trade". "to trade" (infinitive) would be "handeln" which I find not ideal because it can also mean "to act".
It can be discussed if the three top tabs would be also translated, but maybe the words would get too long then:
TRADE --> Handel
ORDERS --> Aufträge
HISTORIE is German already, so there's an English/German inconsistency at the moment.
Here are some suggestions from me as a native German guy with lots of GUI design experience:
Portfolio Tab:
DEX Tab:
It can be discussed if the three top tabs would be also translated, but maybe the words would get too long then: