Seems like the summer will be very intense for the band as some more dates are being added every week on The Cranberries summer 2017 tour:

Yesterday, the band announced they will be playing Guitar Guinness Record (Thanks Jimi Festival!) in Wrocław, Poland on May 1st, as you can see on this link.

A new date was just confirmed this morning at Expofacic Festival in Cantanhede, Portugal on August 3rd.

Just like Marbella (Spain), Landerneau (France) and Trollrock (Norway), none of these festivals are mentioning a string quartet. It is thus yet unclear whether these performances will be performed acoustically or not, though we can note the concert on May 1st is taking place indoor.
Our team is trying to get in touch with these festivals to shade light on this.

Keep on checking our website for more info!