The rumour in question is not at all true - not least because there would've been very little, if any, coffee available to the ordinary infantryman. Keep in mind that such a commodity had already disappeared from the domestic market a few years before the war due to the embargo, and that only the happy few (including party cadres) had access to "the real thing". Those serving in East Africa had easier access to coffee but AFAIK they didn't carry a machine with them!

OTOH some officers (unlike the German military, higher-ups within the Regio Esercito had separate provisions and mess halls) appear to have been issued coffee machines - but whether these had ever been used is debatable.