Swiss currency is one of the most stable in the world. In 2021, the Swiss ten-centimes coin is recorded in the Guinness book as the oldest coin that remains legal tender. The picture shows two sides of the coin. There were no changes in the design since 1879 except the year of issue.
What is the main reason that the name of the country CONFOEDERATIO HELVETICA on the coin is not written in Swiss, but some other language?