Spanish Tourist plates (Alicante)

Hallo, I am new to this forum but would like to learn about car issues in Spain.
I bought my car in Koelln Germany and drove it to Spain with German Tourist plates which expired February Protected content . I am in the US at this point applying for my Spanish residency visa 2 month ago which has not come ,yet. I am wondering if I buy car insurance from a german company will it satisfy the Spanish police if I can proof that the car is insured with my card and purchase receipt even though my plates show an expiration date. I do know that Spanish Insurance companies are not allowed to issue insurance to a car registered in another country.
It seems most answers are for british expats and so I wonder if that would pertain to me as well.
Thanks, Anybody?