Well, they know some of their batteries turn into smoke occasionally and they want to fly again asap. So what are their options?
1) Keep them on the ground until they find the reason for the fire and fix it.
Could take many months or years. Sometimes you just don´t find the problem at all. They can´t afford that.
2) Switch to another battery type.
Takes again many months of development of the new system and certification. Very costly and then you don´t even know if that was the problem or if the failure is hidden somewhere else.
3) Treat the symptoms
The worst you can have is an open fire on an airplane, so you need containment of the fire -> they got the box
Toxic smoke and smoke at all -> they got ventilation
They found cracks in the cell insulation (but thats only a symptom of a faulty battery and not the reason for it) -> they thickened the insulation of the cells
When you "just" lose the APU Battery in flight you don´t really have a problem, because you just need it if the APU and engines aren´t running.
So if you can´t find the reason for the problem, treat the symptoms and try to find a better solution while the customer is back to business.
As long as they can guarantee passenger safety it´s looks good to me.
They won´t stop to work on that topic, because dead batteries are not only expensive but gives them bad press and the plane is stuck on the ground until it gets a new one.
Thats my point of view.