Solar panels are waterproof (how else would they survive rain) as are insulated electric wires. The only challenge is connectors, and there are ways to make connectors submersible-safe.

This is how floating solar is a thing.

China has has Megawatt-scale floating PV at sea too.

I would suspect they are floating on pontoons.

You can see the pillars they are built on in for example https://www.bloomberg.com/news/articles/2022-05-13/china-s-s...

(direct link to image: https://assets.bwbx.io/images/users/iqjWHBFdfxIU/iy93Jvbye2e...)

Solar panels are meant to be water proof, after all they are meant to survive rain storms and melting snow and coastal weather.

"meant to survive rain storms" doesn't really mean the same as "meant to survive flooding", especially not "meant to survive flooding with salt water". For example, a car survives outdoor weather year-round, but you probably wouldn't want to buy one that was submerged in a flood zone. This plant seems to be floating, though, so they stay above water regardless.

Do you have any specifics about the implementation that makes you say that the engineers have not considered this?

Putting aside the salt water, you'll also just have lots of crud and debris on the panels if they get over topped, which then requires cleaning. Unless the rain in that area is strong and consistent enough.

Seems like a weird location to me, but what do I know.