IIRC, they did see it coming. There was a risk assessment that pointed out that having backup generators protected by a flood wall of the height it was was a bad idea if there was a tsunami wave taller than the flood wall. Sadly, it was considered not particularly likely, and a new wall would have been expensive, so nothing happened.

I think when you consider the risk of nuclear plants, it's worth taking into account the culture of the host nation. Japan, with its culture of institutional and individual corruption, is always a bit risky with dangerous industries, as demonstrated by its history of lethal industrial accidents.

I think Germany would be a little bit better, but it's hard to say for sure.

Well, some places catch fire every year, doesn't stop people trying to pretend that that's not normal.