Hello I was suffering with lots of crash from while playing the high elves. Then I investigated and changed the script now it works fine. If you are also suffering from a crash you can try this script
D:\Program Files\SEGA\Medieval II Total War\mods\Third_Age\data\world\maps\campaign\imperial_campaign\campaign_script.txt
Copy the script to this path. Path depends on your own installation. Please back up the old script so if it does not work you can change it back.
Have fun.