Complex sentence: Though not technically part of the constitution it showed that the parties in the Riksdag were able to agree upon fundamental changes of the political system, which transformed the Riksdag from a bicameral legislature into a unicameral one.
Split into simpler sentences: Though not technically part of the constitution it showed that the parties in the Riksdag were able to agree upon fundamental changes of the political system. The reform transformed the Riksdag from a bicameral legislature into a unicameral one.