As you had posted also on QR forum (which is actually not allowed but in this case, its alright)...

UA must advise LH to reload your bag to QR. If UA failed to do that, then the bags might still be in FRA as LH would not have you on their system at all now.

QR can only find the bag when LH or UA enters the missing bag's information on the baggage tracker.

I have an annual (actually 3) insurance policies that help me recover bags as well as help pay for additional expenses when delayed. On one policy, I am covered up to $4K of expenses if my bags are still not delivered within 72 hours!