Yes it was one of those flexi pipes... A pebble came between the pipes just above the activa cylinder and it was stuck there for who knows how long. It slowly cut through the pipes until the inevitably happened...
I believe that the routing was correct and I couldn't find the correct routing on your website.
I had some trouble unscrewing one flexi pipe from the steel pipe but managed with an angle grinder and here is the result.
Thankfully there is a local company that makes hydraulic pipes and they were able to custom make new ones (20€/piece).