Reshade, a tool for graphics enhancement is actively being banned. When you have reshade installed and launch WT, it will remove the .dll of Reshade through the game launcher. You can circumvent this, but then you run the risk of getting your account banned.
The other tool, which this discussion is about, that will show you the range to target on the map instantly giving you an increased accuracy in game is being allowed. Not only that, it’s being featured by Gaijin on their official channels.
They gave us a map with accurate equi-rectangular distances. Nothing stopping someone with calipers from finding distances. I think the automatic updating of range circles on the map IS CHEATING, but manual updating (such as moving the circles yourself) is not. Frankly, it should be a feature in the game for arty-type vehicles. Rangefinders are already in the game, but made to operate poorly on purpose (at least the optical ones are). Nothing stopping you from taking mil measurements using the default sights, along with a size table, and estimating ranges that way. So using calipers (or paint.exe or other programs which don’t inject DLLs) to measure distance should also be allowed. The indirect automatic measure (moving the range circles automatically and providing heading) of distances using the map has not been implemented in game, so I think it shouldn’t be allowed.