I don't mind OmegaT's UI -- it's easier to understand for me than Trados or Passolo, and it runs natively on Linux. It's even used by some translators professionally, and I aim to do that as well. But that's not what I actually wanted to say, SO:
Thank you for that tip with the file filter! That already helped a lot. However, I'm not sure if the keys are supposed to still be displayed? So, the software doesn't extract the inline texts but instead displays everything.