(A) Before converting to Christianity and marrying Jadwiga, the second of Poland's Angevin rulers, thereby becoming King of Poland, Wladyslaw II was known as Jogaila, Grand Duke of Lithuania.
Everything from the tenses and the architecture of words makes perfect sense
(B) Before he converted to Christianity, married Jadwiga, the second ruler of Poland's Angevin, and became King of Poland, Wladyslaw II was known as Jogaila, Grand Duke of Lithuania.
Here too Jadwiga is made the second ruler and Wladyslaw
(C) Before marrying Jadwiga, the second of Poland's Angevin rulers, thereby converting to Christianity and becoming King of Poland, Wladyslaw II was known as Grand Duke of Lithuania, Jogaila.
Here they are making Jadwiga the ruler and not Wladyslaw 2 .
(D) Before Wladyslaw II converted to Christianity and married Jadwiga, the second ruler of Poland's Angevin, thereby becoming King of Poland, he was Jogaila, Grand Duke of Lithuania.
the tense doesn't converge in the right phase becoming married and converted isn't right
(E) Before Wladyslaw II converted to Christianity and married Jadwiga, the second of Poland's Angevin rulers, thereby becoming King of Poland, he was Grand Duke of Lithuania, Jogaila.
It's never second rulers it shpuld be a single ruler , and he was known as Jogalia not the other way round