I’ve tried to find Japanese horror games from the PS2 era that has this same feel, but I can’t :(
Some quick facts:
The VAs for Siren were British, so every Japanese person had a posh accent and didn’t pronounce Japanese words so well
Siren 2’s main setting, Yamijima Island, was inspired by an actual Japanese Island, Hashima island. The Island was an industrial hub for coal mining and was known for forced labor involving Korean and Chinese slaves.
Both games used facial scans from multiple angles to create the uncanny, and horrifying, expressions of the various protagonists and enemies
The Siren games are really unique in my opinion. There was such a lot of effort put into the environment alone that always makes me come back. I never finished one though.
The only games that felt a bit similar to me were the Project Zero games. I even like them a bit more because you are much more able to take the environments in.