The phrasing of the question omits several pertinent facts, chief among which is:
The PCS returned to membership in a governing parliamentary coalition in 1978, with its adherents remaining as part of the leadership group until 1992. In 1991, with the fall of the Soviet Union, the PCS formally renounced communism and relaunched itself Sammarinese Democratic Progressive Party (PPDS). Wikipedia
The party was founded in 1921, was underground until the 1940's, governed in coalition with the socialist party for 10 years, then attempted a coup against the government and then renounced communism. Given that their only time in power was in a parliamentary coalition, it will be very murky what their policies were.
The policy conclusions I would draw from that are that (a) communists are more interested in power than legitimacy, attempting a coup when democratically removed from power, and (b) even the communists recognize that communism is a failure.
Serious note - determining the "policies" of a member of a coalition government in a parliamentary system is non-trivial. Many actions are driven by the policies of other parties, including those outside the coalition - it may be worth it for a party to yield on important principles just to prevent the opponent from gaining. This is, in my opinion, plausible when the socialists and communists are in coalition against fascists. (strangely, they're all statists.....)
In response to OP request for clarification: I'm not drawing a distinction between communists and the PCS. I realize that diminishes the value of this answer for your purposes, but nothing I found in my brief research justified drawing the distinction.