The vetted evidence only comes from one source, just for sake of clarity.
If the information we have is correct, it will pretty much be made almost entirely by Sony, Konami is basically just licensing out the IP to them. But, of course, if this is true that may not be accurate since it's unclear to what level this insider information is and how much they actually know about the actual behind the scenes development. But as of now, it's understood it's going to be a Japan Studios production.
Guess you'd also have to assume that 'one' source also got to RelyOnHorror and DuskGolem (both of which have talked about this in different capacities at different times)?
I mean, Dusk has been talking about Konami talking to major publishers about potentially "working on multiple SH projects" even before Katharsis started going into details, if I recall correctly.
I'm just curious as hell what kind of proof Transistor saw that made him go to bat so visibly here. We'll likely never know, as I assume it could reveal Katharsis' identify for anyone really looking. Still... it rattles around in my mind, haha.