What are the possible ill effects? What are the benefits of doing to now? Maybe it prevents disease, I do not know.
It would depend on how much was cut and what was the size of the shoots/canes/cordons/trunks cut.
Cutting trunks or cordons can bleed out the vine now. It also opens a large entry point for disease (Eutypa for example). But Eutypa also can enter into cuts made in the winter, so larger cuts are better in the very early spring once some sap if flowing. A slightly weeping cut can actually be a bit more preventative for infection during ideal weather conditions.
Cutting shoots and canes has a similar issue, but less so. In fact trimming shoots is one common canopy management system during the growing season. But cutting these too much could prevent the vine from storing energy into it's roots for next year's growth (lacking the leaves it would normally use to do this). So weaker growth and reduced production next year may result.
Vines are pretty hardy. I would just let them be for now. But next year do not let them carry a full crop so they can recover from the cuts this summer.
And put up a "No Trespassing" sign now to prevent further intrusion.
