Helium's a bugger to confine - which is why it's useful as a leak tester - without cooling it to super-fluid levels, at which point it becomes EXTREMELY difficult to contain, even in a 'closed' system.
About the only way you'd realise it was leaking would be when gaseous helium started appearing in the secondary containment, which is, I assume, monitored for just such an event. Certainly no risk of asphyxiation, or 'Donald Duck' there though, it's not an area where life could be sustained anyway.
Bummer. There I was waiting to see what actually happened... So, now a few months wait for 'Universe 2 - the Sequel' to be triggered.
In fact, because the leak seems to have been caused by a couple of magnets suffering 'mechanical issues' due to an electrical element melting - i.e. the temperature differential caused the cooling system to develop a leak (read 'crack'), this could stall the attempt to end the original universe for some considerable time. A year possibly.
Hope they have plenty of spare magnets, this could be an ongoing problem. Things cooled to super-fluid temperatures develop some very odd characteristics. Brittle isn't half of it!