As I have mentioned, this is a minefield. How mould occurs is that moisture is generated during the day by the occupants of the property showering, cooking, drying clothes on radiators. During the day when the air is warm, there is no problem as the air can easily absorb the additional moisture. But during the night, as the air cools, the moisture migrates to the coldest surface in the property which is usually an unused room which tends to be unheated. As you say, it will also condense onto areas where insulation is missing or defective.
Deciding who is to blame is very hard to do and I have seen these cases end up in court.
I would never use bleach on any restoration or clean up job. There are far better and safer products to use including the one you mentioned, Formula 429.