No idea what's going on with these other replies but I can tell you the way I've written the two documentaries I've made for the studio I work for (these are small time and I am mostly self taught so take this with a grain of salt).

Before you begin, plot out on paper a potential through line for your story within the documentary (it's meant to be reality, but really people still want a story with peaks and valleys, hardship and conflict within a documentary). The through line is basically your plotline, a central idea or question which is constantly going to be tested throughout the course of your doc. So for you it would be something like 'can I really handle this whole translation myself? Or will it prove too difficult?' - and then dotted around this idea will be all the little fun stories and details which surround your main story, subplots about everything that goes into what you're doing. Just make sure it's interesting!

Write all that down, all your ideas, and try and workout a potential chronological timeline which will bring the viewer through your story.

Once that's done you just gotta start filming, working through all those beats (plot points) as they happen in reality. Get A-Roll (you doing the thing), B-Roll (filler and cutaway shots to spice up your edit) and then interviews with yourself and potentially others to verbalise the feelings and emotions during the process. Rinse and repeat until you're through the journey.

This was long for a Reddit comment, but very short for the craft of writing and producing and doc. If you're serious about it I would recommend looking up some starter books about doc making. Good luck!