Scorpius is an avid enough reader when the topic interests him, but he mostly leans toward non-fictional works and I don't think he has any sort of favorite because his obsession over a subject only lasts so long.

I'm assuming many stories have been written about the war so Scorpius would probably shrug off any canon-puncturing in that way, just thinking the books were a 'historical' account of the war if someone were to mention his dad or family because he's just briefly mentioned in Deathly Hollows. As for the other way around, he was raised by wizards so he's not very up-to-date with Muggle pop-culture. He did, however, sort of spaz at Nico di Angelo for him being a demigod.

Ron leaves most of the reading to Hermione. Seriously. "The circumstance of Ron having read a book that Hermione had not was unprecedented."

Also, Ron wouldn't mind there being stories about him. Of course it's all about Harry but, hey, he's in there too! So, yes. He'd definitely get red in the ears if you tried to claim he was fictional and argue quite loudly that he is not, thank you very much, but otherwise he'd be totally okay with it.

Since he was raised Wizard, same as Scorpius, he doesn't know many Muggle stories or much about Muggle pop culture so he can't really canon-puncture anyone. Such as his having thought Cinderella was a disease. But now if he met someone like Merlin he'd probably say something stupid like "Merlin's baggy y-fronts" and then stare, open-mouthed, most likely with some sort of sandwich in hand and mid-bite.

Jasper, when, as above, is not pairing off with his wife, does enjoy reading and I think I Millicanoned a favorite book for him but I can't remember what it was off the top of my head. He wouldn't take well to being canon-punctured at all and he handled meeting Jane Austen well enough so I don't think he'd flip out at any other authors or literary characters.