Wiki page on the list of ROC personnel who have been convicted for spying for the PRC. Quite an extensive list.Back on topic, I can't imagine the MSS not activating its assets on the island if armed reunification is required. Taiwan is an internal affair and not subject to the 'non-interventionist' doctrine China applies in its relations with other countries.
The last public case was in 2020, involving 4 retired high ranking officers, including a major general.