Helmet overlays do not adapt to field of view at all. This results in it being misaligned with... everything, basically. A workaround is to stick to the FOV its stuck at: 60°. This works, but i would like the game to be playable when changing FOV.
1. Get in an aircraft. 2. Activate the helmet, so that you can see stuff outside just the HUD. 3. Change your FOV from 60 to anything else. The HMCS symbology remains at what it should look at 60° FOV, while the rest of the image stretches as it should.