1. The leaks are true and false at the same time. Having the information without all the context of the play makes them biased. You had to see the entirety of the play to really understand the info. Yeah, I know, it sucks because beeing able to see the play is a huge privilege. I hope they will realise the filmed version at one point. So... be patient and you will get it.
2. Lyanna, Elia, Rhaegar and Ashara ARE NOT character assassination. In fact, the play give them a real personnality for the first time. Especialy for the women, they only existed through the eyes of men who loved them or hated them. Elia is a dornish princess, of course she is more than a victim, she is a politician. Lyanna is not just a fool girl who died at the end for the developement of male characters, she is more than that, she has here own free will. With the play, Lyanna and Elia became real character, It's the first time (with Ashara, Brandon, Aerys, Rhaella, Rhaegar, etc) the this character exist outside of the eyes of other character with bias like I said, so of course it will not be the same people decribed in the book, they are more nuanced.