Complex sentence: The club could not continue on the old road to success and for decades played in lower football leagues only, with the highlight of three seasons in Landesliga Bayern-Nord from the late 1970s on.
Split into simpler sentences: The club could not continue on the old road to success, and for decades played in lower football leagues only. The only highlight back then was a short period in Landesliga Bayern-Nord from the late 1970s on.