Visited today and charged ad-hoc with TWINT, no issue.
The mystery was finally resolved, the green spaces were indeed for charging stations. The stations were first visible in roaming data around October 15. They are managed by BKW ChargeOne.
There are actually more green spaces than I had previously noted. There's a first group of 6, and then there's another group of 4. There's also space to the left of the very last charging space in the row that's not clearly labelled as either a parking space or foot passage.
There is no EV signage apart from the green paint. But every car parked in the row was indeed plugged in.
The very first spaces on the right are shorter than the others, but there's no warning for that. If you stick out of those spaces, you'll partially block the entrance.
The parking tariffs aren't particularly attractive, as it's 2CHF/h, instead of the 1.20CHF/h for every other space around. You could even plug in from the public parking spaces on the other side of the fence, but surely that's not the intended usage 😅
At the Kursaal West parking entrance they write in big that casino customers park for free. It's not clear if they can also park here for free. It's a longer walk, but I don't think there are chargers in the West parking.