Where do you live?
I have seen problems with furniture up here in this region, especially lately. The summers are getting more humid, which tends to make wood products swell. Then as heat kicks in during the winter and the air is cold outside, then humidity drops, and you get the problem you describe on anything poorly made, like that sub. It is particularly hard on piano sound boards.
Climate change is forcing HVAC systems to become more complex, to avoid a whole host of issues, mold in particular.
So in our new house there is no basement. I decided to invert the house and put the "basement" on the second floor. The HVAC in addition to heat and cool, has an energy recovery unit, tightly controlled make up air and an Aprilaire humidifier for the winter and an Aprilaire dehumidifier for the summer.
Humidifier to left of furnace, and humidifier to the right.
ERV
Make up air unit.
Climate change is making life a lot more complicated and expensive.
To answer your question about repair, that box needs rebuilding and not repairing. As far as other boxes using those materials, yes, they are at risk.
Homes are changing. This is the tank less boiler that supplies the in floor heat. It can heat up to 12 gallons per minute. This is also an energy saver.
I took the unusual step of putting the mechanical room upstairs.