Sony is not related to Silent Hill. Konami owns the Silent Hill brand and Konami publishes its games.
If Konami is really working on Silent Hill games, Sony's involvement with those games would be maximum to get a marketing deal or a (timed? console?) exclusive deal, similar to other 3rd party games we saw both from big publishers and small indies.
As far as I remember regarding a supposed future Twisted Metal we only have 'insiders' claiming stuff with zero facts behind that, so nothing confirmed at all. Lucid game a relatively similar game to Twisted Metal so an 'insider' claimed they were making a Twisted Metal after it, which sounds like a fan guess because that previous Lucid game from Sony didn't perform well so maybe Sony won't want to work with them again or at least repeating that formula.
Firesprite hired many people, including some from Lucid including a game director. So following that -probably fantasy- narrative of 'Lucid is making a Twisted Metal game', then some 'insider' probably guessed they moved that supposed project from Lucid to Firesprite and created that 'changing its developer' claim again backed with nothing more than a guess. It could make sense, but we know Firesprite is already working on 4 games not counting this supposed Twisted Metal. We know they have a lot of people, but 5 games at the same time doesn't sound realistic.
I bet that there isn't any Twisted Metal game under development.