@Simetrical
Use: "C:\Games\Rome Total Realism\RomeTW.exe" -sprite_script -show_err
so it shows error reports.

generals_horse romans_julii generals horse is wrong. The 3rd mount type parameter is for mounted units only, NOT for the mount itself (generals_horse in your case). Leave it out and it should work.

@lt1956
Not sure what you mean, but it doesnt use faction colours anywere. It only uses the texture you specified for the given faction.