The Venetians were not present at the same time. The last Venetian outpost was Crete and Venetians left Crete in 1669. However, they remained in Corfu, Zante etc.
The Rousso family (sometimes they call themselves Roussakis for no specific reason) can be found predominantly in Crete, around Heraklion and around the Village Malia. I have many Rousso relatives (grand aunt married Rousso). If you search you find. You need the names of wives too. Wives names will give you more info than the name Rousso.
The family Rousso has two characteristics; 1. They love land and agriculture. and 2. They are outstanding business people (Merchants) Instinctively, know how to negotiate good deals).