Insulating Eternit Asbestos Facade

Then yes, but ten percent of the "asbestos" in forum posts is asbestos, so I rather suspect artificial slate here. It's not only the case that not everything that glitters is gold - but also not everything that comes from Eternit is asbestos.

If the OP talks about asbestos, it will probably be so. But no one is stopping you from telling the OP something else if you want.

Hello,

my main concern is just that the Eternit panels are not visible.

So far so understandable. If it is actually asbestos, I would not only visually conceal it but actually redo it properly right away. Sooner or later that will have to happen. Better to think it through calmly now and renovate without pressure than, in the worst case, to hastily patch something up on a crumbling facade in a few years.

I'm just not sure if my idea could cause condensation to form under the Eternit panel construction, which could attack the basic structure or cause mold. At the bottom of the construction there is a lift circulation grille

That can very well happen. The side facing the ventilation is cold, the outside is insulated again. That way you wouldn’t visually notice the ongoing decay and one day be surprised by loud banging when the structure has completely deteriorated.

As already wrote, I would not add more weight to an untrustworthy construction or its structural condition.