My issue is that I don't know why Ensemble processes incoming data in the wrong encoding.
Update: Issue was solved, I think, see my answer below.
our customer uploads UTF-8 encoded CSV files to our sFTP server. When I view the files on the server side, the scandinavian characters Ä and Ö (A and O with two dots on top of themselves, respectively) display correctly in the source file. When Ensemble downloads the files using a FTP Service, the characters display incorrectly in Ensemble.
I am unable to pinpoint the reason for this behavior and I was hoping this is easily solvable.
Edit: two additional details that I did not remember to mention but Gertjan brought up: