Hello,
When i go on my service record i have won a game on every map and also won a game with each leader, however the achievements wont unlock.
I have took about 2 years to do this, and i have done it over multiple Consoles, but on the same Gamertag and online, (My service records shows all the wins).
Can someone help?
I would try searching on the old halo wars forums on the halo wars official site for that sort of help, don’t think anyone here knows anything about it. try PM a mod too and ask in the waypoint sub forum as that is much more visited by the mods than the halo wars sub forum.
If you did it on multiple consoles without transferring hard drive data, that would be the problem.
Cloud came to the Xbox give or take 1 year ago, your games from 2 years ago wouldn’t count if you didn’t save the game to a portable hard drive.
Just logging in doesn’t save/accumulate your campaign progress. 
I did the same thing with Portal 2 years ago and was wondering the exact thing.