Yes, we know, but it was not confirmed.

On the website we found this.
https://ska1030.be/festival/ouverture/

This suggests that they may have postponed the opening date a bit.  Until it is confirmed, it may be a bad idea to update the map if it is not true.

Opening notes anonymously to suggest "errors" or "failures" of other mappers to map properly is not beneficial to OSM.  Contributions are welcome if you can bring some useful information: do some research (online or by calling or going there) to confirm if the place is open, and tell us.