do Enjin Devs still contribute git-hub activity?
I could be wrong here but I don't think they are much active on the GitHub. But to get an official answer from the team I suggest you contact them on telegram.
if they are not active on github, the development of their project stops ?,
but they still always give news on social media, facebook, twitter is always active, and that is the positive
No the development is still active be assured of that.
But to get the proper answers I think it would be best if you ask that question in the telegram channel