Having the exact same problem, AA runs fine but Spearhead and Breakthrough do this.
Already tried a bunch of things regarding config files, compatibility modes and gpu settings.

Did you happen solve the problem?
Anyone else an idea?

You have to change all 3 MOHAA folders. You change one but you have to do it with the others. This is how I did it

Go to C:\Program Files (x86)\GOG Galaxy\Games\Medal of Honor - Allied Assault War Chest\main\configs and open "unnamedsoldier.cfg" with notepad. Add these lines

seta r_customwidth "X"
seta r_customheight "X"
seta r_mode "-1"

Change x to whatever resolution you want. If the game changes back to its original settings. Then right click "unnamedsoldier.cfg" and put in read-only.

Now the game will look horrible with its old FOV. Go here for that http://www.wsgf.org/dr/medal-honor-allied-assault-war-chest

This will fix it, use compatibility settings "override high DPI scaling behaviour." Scaling performed by: Application.

(Make sure you add these settings for all 3 executables, for each game.) These DPI settings worked for me, add these settings for all 3 game executables.