You are misinterpreting the information here. Neither Firefox nor Ubuntu are doing anything to your root directory. The behavior described and what you are undoing is that your storage device is being made available at two locations: both at / and at the hunspell path.

Unfortunately, you’ll probably have a hard time finding a new Bolt at this point. They’ve just stopped making them and dealerships haven’t really been able to keep any in stock for months in my neck of the woods. Apparently they will eventually come back but the timeline hasn’t been announced so probably several years.