Turns out not only the uix86_64.so and cgamex86_64.so downloaded from japp.jkhub.org (not to confuse with the uix86_64.so and cgamex86_64.so files from openjk) are to be put in the japlus folder where the game is installed but also in ~/.local/share/openjk/japlus/.
I did notice some log errors saying that the game could not find these files in ~/.local/share/openjk/japlus/ but to me that was not an issue since the logs immediately said after that that it found them in ./japlus/. To me the search path mentioned at the beginning of the logs were simply the places the game was going to search for stuff, not places where files absolutely needed to be. Especially when it's looking for the same files at two different places...
Also I must admit that JA++ is pretty nice. It does indeed bring the special moves from JA+ (provided you download the cl_lua_japluscompat.pk3 file from japp.jkhub.org) which is quite nice. The real grappling hook is also indeed there.
I do wish there would've been more info on how to install JA++ though.
