Can attest to that. Had similar situation - Being DE tax resident however working for my own company that is not based in DE.
I had just a simple question - when and how do I pay my taxes here from the money I bring from my company that is not German. And they could not help me because they really could not understand that someone might be living in Germany but not working in Germany.
In my current specific situation there are no coworkers from Germany.
I didn't even know that a US-based company can give me a German contract. Do you know the specifics how the stuff got deducted automatically (except the taxes)?
I don't know any of the details of how the company made the employment work. If you PM me I will give you the name of our German accounting firm which handled everything.
It's because most German beurocrats are garbage when it comes to laws related to outside Germany.
Personal take on tax accountants or anyone in that profession: They're more than useless. As parent poster said, 99% are form fillers, so if you tell them that you're working for a US entity that is not paying income tax on your behalf some of them will flat out say "but that's not even possible" (yes, someone told me that). My tip is just to read up on some topics, band together with co-workers in a similar situation and then just do the taxes yourself using one of the popular services.