經濟學人里的句子，請問第二句話的語法是否有問題？

But in 2012 the KNU signed a truce with the army.

It laterjoinedthe peace process, progress on which has been touted by Aung San Suu Kyi as her priority since she became Myanmar’s de facto leader in 2015.

It laterjoinedthe peace process, progress on which has been touted by Aung San Suu Kyi as her priority since she became Myanmar’s de facto leader in 2015.

逗號后為非限制性定語從句修飾the peace process。關系代詞which指代the peace process, 在從句中做介詞on的賓語，介詞短語作從句主語的定語。