I do not know what’s behind the game logic, (
have not played WWI yet), but I’m sure there was not logic behind that happened in 1914-15 with Italian intervention.
Austria was a the natural enemy of Italy along the full XIX century.
Italy had an alley in France along XIX century in wars against Austria. Britain supported the Italian unification process too, at a political level.
In 1866 Italy and Germany, (Prussia) entered an alliance against Austria. In 1870 Italy proclaimed the unification under Savoia Crown: that same year Italian Volunteers lead by G. Garibaldi were in France to defend the Republic against Prussians.
At the beginning of XX century Austria was till controlling Trentino, Friuli, Istria, Dalmatia. They were Italian language and culture regions of the former Republic of Venice.
Austria was hated and till considered the natural enemy!
In 1911 things changed. Italy entered war against Turks for the conquest of Libya. The change in the balance of power in the central Mediterranean leaded to worsen relationships with France, (controlling Tunisia at that time), and Britain. Political isolation carried Italian government to active alliance with Germany and… Austria. This did not influenced natural hostility for Austria quite common in the people as in the intelligenzia.
When WWI begun Italy entered a neutral position, as allowed by alliance terms with Central Powers.
The country was politically divided in parties: in favor of a long term neutrality; in favor of entering war against Central Powers to liberate Trentino, Friuli, Istria, Dalmatia; in favor of the respect of the assistance treaty with Central Powers.
Secret negotiations with Central Powers and Entente leaded to a stall: at some point both sides were closed to offer Trentino, Friuli, Istria, Dalmatia to Italy. BTW, Istria and Dalmatia had been granted to Serbia too, by Entente powers!
Possibly, it was the street to take the decision: it was an impulsive action triggered by Dannunzio and other tribunes populi to lead Italy to join the Entente!
In game term it is not realistic having Italy entering war in 1914. 1915 is to be the decision year, with opposed sides NW influencing Italian political decision but with the random event “Dannunzio and the street” possibly moving Italy at war against Austria.