How to import an OBF map file into OsmAnd? The map file provided by OsmAnd for a particular region has inaccuracies, so I would like to use this fixed OBF file instead.

How to do that?

Below is the procedure described on the website providing the fixed map, unfortunately it did not seem to work (when viewing the whole country the regions downloaded within OsmAnd (official OBF files) are highlighted in green, but the non-official region does not show in green).


  First, uninstall any standard OsmAnd maps of the region, because they
  will conflict with your custom map.
  
  Copy the map file to the Android device. If you have downloaded the
  map file from this site, be sure to unzip it first.
  
  For example, use a network-capable file manager, such as ES File
  Explorer.
  
  Put the map into the osmand data folder (you can check which it is
  under Settings → General → Misc → Data folder )
  
  It seems that the map needs to be renamed once within OsmAnd's Map
  manager (Map management → Local → Select your file → Rename) before it
  is actually recognized by OsmAnd.
  
  Afterwards, don't forget that you have to change the description
  language (Configure map → Description language) to English to see the
  transliterated place names.
  
  Also, as the base world map has not been created using
  JapanMapTranslate, you will need to zoom in a bit so that your local
  map is actually used.


Note: Unlike my other question How to import a .obf POI file in OsmAnd this question is about maps, not POIs. Answers at that question do not solve the problem here.
To view OBFs that I didn't download through OsmAnd, I first had to change the directory where its data is stored to one where I can push stuff (non-rooted phone).

For that, I first went to Settings > General settings > [Miscellaneous] Data storage folder and switched it to "Manually specified...". I decided it would be /storage/emulated/0/osmand as this is a place I can see when connecting the phone to my laptop. OsmAnd asked whether it should move all its config files there, I said sure, go ahead.

I put the OBFs directly at the root of /storage/emulated/0/osmand. It lost all the maps I had downloaded through the app after the folder change, so I had to download the world map again, for example, and it ended up at the root of the folder too, that's how I figured it out.

It may take an OsmAnd kill and restart for it to detect new maps, and the trick above of renaming the file through the map manager indeed made it be inspected by OsmAnd and marked in green as a region for which a detailed map was available. Even before the renaming, its content would still be used though, so as soon as you see something corresponding to your OBF in the map manager, everything should be OK.