As far as I know, the various accordions I have are been no more than an honest middle of the road in level, yet they all have coped with my local climate, ranging from approximately 80 to (newest) 30+ years. All without evident damage; all made in Italy; all PA, 41/120.
Only one brand name is still in existence, and that one has undergone several changes in ownership, so little point in specifying names.
But all have shown the capacity for surviving temperatures ranging from -3 to +46 degrees C and relative humidity of 5 to 99%.
So, I'm inclined to think we have a general tendency to seriously underestimate the hardiness of our favourite instrument!
Absolutely.
I heard often that the accordions from the golden age were made to last forever (I saw once an old Weltmeister still working even thought it had a crack on its wooden box) , but unfortunately quality has gone down hill in recent years, generally speaking.