I would like to ask if it is acceptable to call an event "English in the town" putting the emphasis on the contrast that is is not held in the classroom. It is the name of the event, i.e. it should attract and draw attention to it. Thank you.
Both are possible, but "in town" is significantly more idiomatic.
"In town" not only means "in the town, as opposed to outside in a rural area", but also strongly connotes "visiting, on hand, close by". It's understood to mean "in our town".
Hey, kids! There's a Santa Claus parade in town. Do you want to go?
"In the town", on the other hand, requires the mention of a specific town.
There is much to see in the town of Rochester, New York.
In the countryside there's little to see, but in the town there are several museums.