Complex sentence: In particular, Knudsen's work on language reform in the mid 1800s was important for the 1907 orthography and a subsequent reform in 1917, so much so that he is now often called the "father of Bokmål".
Split into simpler sentences: In particular, Knudsen's work on language reform in the mid 1800s was important for the 1907 orthography and a subsequent reform in 1917. So much so that he is now often called the "father of Bokmål".