Visited yesterday without charging.
Swisscharge doesn't make it obvious where the charger might be, but there weren't that many options. They were not outside, and there's only one underground parking.
Swisscharge name it "Parking Leuengasse" but on the sign for the parking it's called "Leuengarten".
The parking is indicated for visitors of the buildings above it only. There's an exit with the restaurant name, but the signs on the machine ask the restaurant guests to park elsewhere. All the regular parking spots have signs telling for which building number they are reserved, but the charging spots don't have such marking.
There is no gate, but there is a parking meter. 2 hours free, then 1CHF/h. The parking closes at night.