First of all, we should remember that the script that was published and released was NOT the finished story. It was the FIRST DRAFT that was given to us. It was the Special Rehearsal Edition. The final story with the repairs and tweaks will be published in 2017 as the Definitive Collector's Edition. The Special Rehearsal Edition was for rehearsal of the play and the previews. The tweaks were suggested by the audience of the previews. The previews were the showings that happened before the play officially released to ask for reviews and changes in the plot and the special effects. So, in fact there are many different versions of the script with slight changes as the previews progressed. The changes being from dialogue to major events alongside special effects of the play. So, there are 20, 30 or maybe even more versions of Harry Potter And The Cursed Child with varying plot and story contradictions lying out there somewhere, either at the theater where the play is going on, or at JK Rowling's or at John Tiffany's or at Jack Thorne's house. The final, canon version of the story will come out next year. Atleast JK Rowling gave us something. If she had decided to print the Definitive Collector's Edition only, we would have gotten nothing this year, except for Fantastic Beasts. The final story was prepared around the 22nd of July, so the final story would have taken atleast months to be published worldwide and we would have had to wait till next year for the story. Atleast we got something, even it wasn't canon and most of the story will be replaced by something else. So, in conclusion, most of the contradictions will have been repaired by the next edition of the Harry Potter and the Cursed Child.