It seems that the main registry key for Close Combat 2 isn't actually what is being read by the game, so if you try to modify anything in "HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\microsoft games\Close Combat\2.00" then it won't do anything.

Instead, you need to modify the ScreenX and ScreenY values in "HKEY_USERS\S-1-5-21-2679232830-4228635532-1208208188-1001\SOFTWARE\Classes\VirtualStore\MACHINE\SOFTWARE\WOW6 432Node\Microsoft\microsoft games\Close Combat\2.00"

Also, the "S-1-5-21-2679232830-4228635532-1208208188-1001" may not be the same for your system. What I did to find this registry entry was to "Ctrl-F" and Find "ScreenX" with "Values" checked and "Match whole string only" checked.

Hope this helps somebody out there. With this, you can run Close Combat 2: A Bridge too Far in full 1920x1080 resolution. One more thing, don't click the "Magnify + Zoom In" button in game after using a non-supported resolution, because it will trigger a bug where everything is displaced and will eventually crash the game.