Complex sentence: International recognition of the ROC gradually eroded as most countries switched their "China" recognition to the PRC while maintaining unofficial ties through representative offices via institutions that function as "de facto" embassies and consulates.
Split into simpler sentences: International recognition of the ROC gradually eroded as most countries switched their "China" recognition to the PRC. However, numerous other states maintain unofficial ties through representative offices via institutions that function as "de facto" embassies and consulates.