By "modding API" in my first edit I was actually referring to MCP. I couldn't think of a better description. The mods I mentioned aren't indeed by Japanese dev

By "modding API" in my first edit I was actually referring to MCP. I couldn't think of a better description. The mods I mentioned aren't indeed by Japanese developers but I can now see how my wording is wrong. I meant to say that the Japanese modding community is also active and doing wonders. Thank you.