The v1.2.1 patch fixes the following issues...

Stronghold Crusader Extreme (v1.2.1):

10,000 people limit fix - Upon reaching 10,000 people the game would
crash out.

2000 people standing on one tile in the game would crash the game.

A very obscure crash was fixed, which occurred when attempting to link
to a multiplayer game.

Stronghold Crusader (v1.2):

Italian speech fixed, for Stronghold Crusader Warchest characters.

IMPORTANT: Please download the correct patch for your version of the
game. If you purchased the game via digital download please obtain the
patch from the partner site you purchased the game from.