I found this for syntax highlighting of AngelScript in Notepad++.

I just dropped it in the program folder\plugins\APIs, and then I am able to select it for a specific file by clicking Language -> AngelScript. It would be nicer if it could be made so that it automatically identifies .j2as files as AngelScript, but I couldn't get it to work and I'm not really intending to try coding anything myself at the moment, so I'll leave that up to you.

AngelScript syntax highlighting