I think that two months is a short time for an alliance, don't you think it should at least be a year? I believe that unless somebody overthrows the Starks, the Tullys should be permanently allied with the Starks, considering that the Tullys are sworn to the Starks. I know it technically wouldn't be realitistic to be permanent, but of course, neither is people never aging, or not having kids, or alliances lasting 3 months. If
had never happened, the Tullys would be sworn to the Starks for a long time. I guess you could create a claimant quest to overthrow the rulers, and that could end it. It annoys me how in native the factions go from warring to being allies and back to warring so quickly.
A small complaint about the mod, shouldn't each of the Free Cities be controlled by its own individual faction, considering they are all independent cities?
Aren't you asking too much for a beta? 
No. It's just a few extra faction to create. You don't have to go into the same level of detail as the Westeros factions. That is assuming you're going to include some part of Essos. You could just create a few units for each faction, design the scene for each city, and make a few lords of those factions. I didn't say it was easy, but personally I think that you should create Essos until you've finished Westeros.