I use the AngelScript API somewhat unconventionally so I'm willing to test this aspect of JJ2+. I can also test anything related to the network (like jjSendPacket) as long its the basics since I don't get involved in the competitive scene nor do I play multiplayer often. Off the top my head the only parts of the AngelScript API I might not be able to give much insight to is level design-related since I don't have much experience in that.

Hosting a server is possible, but inconvenient. This is because I have to change a setting in my gateway that not only disables Wi-Fi but also takes a long time to apply, so I can only host during specific timeframes. I haven't had the chance to look on how to resolve that.