Hello FNS
I do work in the station of Lucerne, I am one of those guys being there wearing a yellow vest.
The XXL lockers are likely to be available again at night, they are often all taken during the day. Nowadays everyone is travelling with an XXL suitcase.
Tracks 14/15 share the same platform, however the sign for track 15 is barely visible when arriving on platforms 3 to 10, while the sign for plattform 14 is well noticable, thus I said platform 14.