Better late than never - here are the additions needed for definite grading. I used the french game but same versions as the OP (AoM 1.10, Titans 1.3).
As was reported in other solutions threads, the Wiki needs to be corrected : the syntax for setting a custom res is
xres= yres= (and not -xres= -yres=). And it's much easier to edit the game's shortcut anyway.
Is 1280x768 supported? Yes.
Are 1280x800, 1440x900, and 1680x1050 supported? Yes.
Are 1280x720 or 1920x1080 supported? Yes, both are.
If so, how's the 16:9 support?Hor+
1360x768 (16:9)
==Cut scenes==
The intro/trailer is a bink video that plays in a fullscreen 1024x768 independently of the in-game resolution (thus stretching on widescreen displays not equipped with some sort of "fixed aspect ratio" scaling).
As can be seen on the screenshots, real-time rendered cut scenes are vastly Hor+ but because the theatrical letterboxing shrinks as the AR gets wider, they're a bit Vert+ too.
==Multiplayer support==
No problem hosting/joining games in all ARs.
==Surround Gaming Support==
Same method, add xres= yres= to your shortcut's Target field. (The SGU entry only forces windowed mode and doesn't even list the Titans expansion, so don't bother.)
Hor+ gameplay, stretched UI except the minimap.
5040x1050