If we are to trust to published statistics form other countries for 2018, and using for the Swiss system, the 2021 data mentioned in the article: "about 92% of passenger trains were on-time" this would make it for punctuality, somewhat middle of the league. Behind Poland, Greece and Bulgaria for example.
This is assuming being on time is: "a delay of five minutes or less". For Swiss network the article uses the definition: "a delay of three minutes or less".
"Share of regional and local passenger rail services classified as punctual in Europe in 2018, by country": https://www.statista.com/statistics/1255048/punctuality-regi...