I've created a fresh game and I've installed all of your plugins and exacted the parameters from your plugins.js, but I can't seem to replicate this error.
If the problem is indeed from an outdated library and Steam won't update your libs, I have a suggestion. Maybe you could visit the completed games and download the newest one and harvest the game's rpg js files and libs folder from its www folder. I'm not sure why, but this suggestion seems a little unethical. The first and foremost solution would be to fix Steam, but I don't know how, when or what about that.