5.11-2 Is it possible to reproduce a work of art which will be object of an exhibition starting in three months on the cultural blog of a journalist?

In principle no. This is because the exception of art. 28 CoPA is valid only for current events, which means events that are in course or just finished. The situation could be different if there is something new about this future event, which makes it “current”, for instance the organization phase started: nonetheless, only works that are perceived at this phase can be reproduced under art. 28 CoPA.