Complex sentence: He was not the first important German lutenist, because contemporaries credited Conrad Paumann (c.1410--1473) with the invention of German lute tablature, though this claim remains unproven, and no lute works by Paumann survive.
Split into simpler sentences: He was not, however, the first important German lutenist, because contemporaries credited Conrad Paumann (c.1410--1473) with the invention of German lute tablature. However, this claim has yet to be proven, and no lute works by Paumann survive.