I only had anecdotal stories of people signing binding agreements in EU countries where they were illegal, and then leaving (breaking the agreement) with no follow up from the company. At the time we made a conclusion, that the company was well aware of illegality of the agreement but used it as a scare tactic.
This forum is way below the pay grade you need to get the legal answers you want. I think I would try to speak someone who is working in that field. Lawyer?