The likely decade of court losses was clearly inbound, it's why Monsanto was sold off. There was going to be no upside to the stock in that atmosphere, so a nicely priced sale was the optimal out. The court losses you're referring to were well set before the sale. The roundup trial for example was filed a year prior to the sale. The lawyers for Monsanto and Bayer very likely knew how bad it was, they had a better view than anybody else.

Bayer knew exactly what it was buying: they're going to trade a mere year or two of Monsanto profit (maximum), across a decade, to pay for the overall legal hit. In exchange they get to buy a fortress of intellectual property and one of the globe's dominant AG chem / AG biotech businesses (on a planet that will add ~3 billion more people to feed in the coming decades).