How would I find trust worthy parents with kids in middle school in Venice, Italy

Do you speak any Italian?

No not really. I was thinking maybe someone from the states might be able there teaching or they might know some English. We try but aren't very good. We know some French but unfortunately not much Italian.

Are you a teacher? You might try contacting the US consulate in Venice (if one exists) to see if they could establish contact. But they could be just as suspicious of you as you are of them. Who vouches for your trust worthiness? Also, Venice doesn't have a large population because of a large decline over the years in people living there and the young families may well be living on the main land. If you call the school they probably don't speak much English either.

Not sure if it is part of your trip but you might have more options in a city like Florence.

Have you looked into Servas?

So then why not contact the English language schools in Venice? Google English schools in Venice and English language schools in Venice and several will list. Each has a website with email contact form and/or Facebook page where you can contact the school and make your request to meet teachers with daughters same age as yours. Make contacts now while you are still home so you have time to communicate and build relationships.

Seeking "trustworthy people" to interact with would require you to prove you, too, are trustworthy.