Visited on May 7 and charged with eCarUp, no issue.
Signage was added! It now says access is only for the visitors of the houses and offices around, max 6 and is paid. The tariffs aren't posted, but by using ParkingPay it seems to be 1CHF/h.
No idea if just coming to charge is also a justification for parking here.
There are still no parking spaces designated as charging spaces.
When trying to stop the charge from the charger screen, it asks you to type a code. I have no idea whether "Please enter 0000" is supposed to be a placeholder, but if you literally type 0000 then the charge stops. This is the most useless protection ever. And there's already an "Are you sure?" confirmation step, so it's a 7-press operation to stop the charge.