And on his website he writes (to clarify the above)

I have only tested this on EV4. Somehow on my EV4LDX when I boot it up it always boots up in English. In response to everyone's wishes and needs I will release this as it is, imperfectly. Consequently, on the EV4 the messages seem to be displayed in (false) English. For use on the EV4 a bin file has been put into the EV4 folder.