Unfortunately, Mendix does not have the concept of an array of strings. It only knows array of objects. So to consume this REST API you need to create a Wrapper/Helper entity with a string attribute and use this in the import mapping.
Hope this helps,
I dealt with something similar a while back. It was a WSDL but the concepts still apply, perhaps this can help you.
thanks for answering that fast.
Good to know that arrays of strings do not work per se in Mendix. Unfortunately, I never worked with wrapper entities before. Is there any example of how this would look like?