Hey Pierre, we think that we've finally found out what your issue is. If we're right, you're also missing out on various custom creatures. From my own tests, we're pretty sure that the game language currently has the potential to break part of the map. As soon as I changed the game language to my native language, German, my Grappling Hook stopped working and I stopped getting a few custom creatures, instead seeing some that weren't supposed to be there during Spring. The moment I switched back to English, everything started working again like it's supposed to.
So now we'd like you to set the game language to English for a bit to confirm our theory. We're 99.9% certain that the grappling hook should start working once you change the language, and that you should get more of the custom creatures. If you want to keep the client in French without missing out on the features, setting up a server for the map should be a possible workaround until Dan can fix all the relevant blocks in the command center (which will most likely not be in 1.8 yet since that update is late enough without having to go over that many commands yet again.)