It seems that no, I'm also wondering if you can use it with the new version of NW.js.
The plugs are very good, but there is no new version :-(
I've bought Steam4C2 full a few months back, been using it since for my game "DriftKing2D" on steam (sorry for the ad). Everything works as intended except for one thing which is why i'm here: One leaderboard works just fine. the newly added one doesn't whatever i do. And some achievements don't seem to unlock. While it's pretty much the same code, just changed to the other achievement ID.
I'll get back to this if i find the answer. Also could use a tutorial/manual but the scirra store is down.
Edit: I fixed this a while back with a custom timer. Just to make sure only one achievement/leaderboard will be checked at all times. (Check achievement 1, add 1, check achievement 2, add 1, check leaderboard 1, add 1..etc, and then return to 0 and repeat.)
This plugin still works as of today. RIP C2 (Soon) https://www.construct.net/en/blogs/construct-official-blog-1/sunsetting-construct2-1505?utm_campaign=blog1postemailsub&utm_medium=email&utm_source=1505&utm_term=txt4-read-ashley%27s-post