Here are a few German/Czech composers that lived in the time of our protagonist in Holy Roman Empire that were very popular back then. I made this topic so that hopefully devs can do a research and add their music in game (because this is the same historic period).
Jan of Jenštejn (Jan z Jenštejna)- Czech composer wildly known in medieval Bohemia because of his role as Archbishop of Prague. His music in compelled into a book “Die Hymnen Johanns von Jenstein, Erzbischofs von Prag”. Died just 3 years before game plot.
Záviš of Zápy (Záviš ze Zap) - Czech composer which lived in the time of the plot (died in 1411). Its said that he made one of the most valuable Czech medieval songs. His compositions were based on melodies of some older liturgical works, kept in the archive of the St Vitus Cathedral in Prague. And because he lived in the time our protagonist did, his music would represent that period perfectly.
Hugo von Montfort (1357 – 1423) , Famous Austrian composer. Although he was German, he was still known for his music/poetry/politics in Holy Roman Empire, including neighboring Bohemia.
Oswald von Wolkenstein (1376/7 – 1445). One of the Best known Holy Roman Empire’s composers in the first half of 15th century, and most famous of all 4 composers. He was famous around Europe back then.