Insead, if you comment the following lines by deleting the # this way:
[multiplayer]
comment/uncomment following line to disable/enable hotseat campaign
playable = true
faction mask for setting default starting factions in hotseat campaign
factions = 1 = england, 2 = france, 4 = hre, 3 = england+france, etc
[hotseat]
disable start turn scroll in hotseat campaign
scroll = false
disable forced separate human faction turns (including diplomacy) in hotseat campaign
turns = false
enable cheat console in hotseat campaign.
disable_console = false
specify password for administrator access to the dev console when console disabled. Change 'password' to a suitable password
admin_password = password
enable camera updates during ai turn in hotseat campaign
update_ai_camera = true
enable voting in papal elections in hotseat campaign (only first valid human faction votes)
disable_papal_elections = false
disable forced autoresolve all battles in hotseat campaign
autoresolve_battles = false
disable diplomacy validation for incoming propositions
validate_diplomacy = false
disable forced relevant hotseat options to be saved with game.
save_prefs = false
autosave hotseat game at start of players turn
autosave = true
save config file in save dir containing information about next players turn
save_config = true
## close medieval II directly after a hotseat autosave
# close_after_save = true
## sub directory name for hotseat save games
# gamename = hotseat_gamename
## ensure game data files used in previous save match current campaign data files.
# validate_data = true
## prevent game to load if savegame or data validations fail
# allow_validation_failures = false
Then switch the file to "red only". The problem it's solved: during the AI turns, if AI attacks you, the game stops and you can play the battle.