Hi Fabian,
I asked DocuWare Support about this and they just said "go ahead and empty the folder" so I guess there's nothing important in there, which makes sense because it's called "Temp", after all.
Import jobs live temporarily in C:\ProgramData\DocuWare\Jobs and I'm currently dealing with that folder bloating for a completely different project (it's been one of those weeks). Here's a kb on how to manage it: https://support.docuware.com/en-us/knowledgebase/article/KBA-35020