Maybe it's necroposting.
But at the beginning of 2018 I started to write the documentation of the maps data.
At the moment it is completely finished for versions 3.2+ and 3.3+
I never completed the description of maps and objects (bjo) to version before 3.1 branch, but in this last version of the game, they are no longer relevant, because maps store everything in JSON.
The only drawback is thats need to be translated from Russian into English.
I also wrote a library that works with maps, can read them, make previews in a color scheme similar to the game, convert json->bjo and Vice versa bjo->json, automatically on the fly add spectators to the map, and even made a preliminary map generator.
This library already works on my website: https://wz2100.euphobos.ru/maps/
If someone need this, perhaps later I will publish on github, after I bring the code in order.