If the problem is fixed and the insurance is paying most of it, you got a hell of a deal. They could of ripped out your walls while pretending to search for the leak and charged you in the thousands. And you would of had to pay it too.
What everyone seems to be over looking (use adjacent real estate for building ) (Property owners have the right to mount ladders, scaffolding or similar on or over a neighbouring property),
I really doubt you'll find anything illegal about a crane swinging over your property, nothing is mounted on or over your property.
I agree 100% with looking for a new job, BUT! Don't leave first without a fight. If you lucky you could just drag them down and out with you. Who gives a shit if one is married to one of the Betriebsrat guys, he'll feel like shit when his wifes name gets dragged across their desks. and what do you think the big boss will think when he see's this.
Don't wimp out and walk. fight for your rights.