Tectonic plates don't move nearly quick enough to be a concern in the span of 100k years. A spot square in the middle of a plate is going to be safe from earthquakes for millions of years.

And not to mention, how does ground vibration bring sometimes buried under 500 meters of solid rock back onto the surface? Earthquakes shake the ground, they don't dig deep boreholes.

You’re incorrect about the middle of tectonic plates being safe from earthquakes by definition. Locating naively built skyscrapers in New Madrid, MO, for example, would be a bad idea. [1]

On a geological timescale, tectonic plates occasionally rift down the middle, both successfully (East Africa) and unsuccessfully (a failed plate rift produced the Great Lakes).

With that said, identifying strata that are going to remain seismically stable for a looooong time is a solved problem, and earthquakes generally damage only those things not attached to the (moving) earth.

[1] https://en.wikipedia.org/wiki/Intraplate_earthquake

Yet, all the attempts to store nuclear fuel underground in Germany proved so catastrophic that they had to scrap all of them and restart the selection process.

And this was because of earthquakes? Germany foolishly stored it in an abandoned mine, rather than impermeable bedrock.

If we continue on the current path there will be no society at all. This argument is seriously f'ed up for so many reasons

There are water around mines that will be toxic to human life until the sun collapse and the earth burns up. People will have to be aware of those dangers for as long human exist, unless humans mutate enough to tolerate lead and sulfur in their fresh water.

How should we communicate to those people of those dangers?

In the very long run we don’t.

We simply trust that people in the future check their water for safety, or avoid drinking from water sources that correlate with illness.

We do this now, and humans have done it for millennia.

We need a banner that says "Don't drink the water full of dead deer"

(Hum, I hope that they will not have tiktok)

Lead and sulfur are relatively easy to remove from water. Wildlife, however, will be affected by that. We have bigger issues.

We can filter it out, but unless people know that the water is toxic then they might still be harmed. How do we inform the people of the future of the dangers that contaminated fresh water has, and how do we do that for billions of years into the future?

Nuclear waste disposal has already been solved at the Waste Isolation Pilot Plant.

https://en.m.wikipedia.org/wiki/Waste_Isolation_Pilot_Plant

The flora and fauna in the Chernobyl exclusion zone appear to be thriving.

In some cases, yes, in other it seems that they are sink areas that are simply constantly being nurtured with migrant animals from the surroundings (Some birds for example). Is complex.

And we need to remember that some people was poisoned just a few months ago for digging trenches in Chernobyl in the middle of a war. The danger is still there forty years later.

Poisoned is a relative term. The rates of cancers and deaths from the Chernobyl disaster varies by an incredible amount depending on what source you look at.