It's been less than 12 months since the official release of Ch5 full, not beta. SUre it's been longer since the plot moved forward, but the time since the last update to the OP is what it is.
Regards Nika and Nami, we're all wondering how Ocean will explain the situation. My guess is that we'll find out what the deal between them is when NIka starts talking about the other deal he has with Nami that no one knows (if you take her on the night walk in ch4.5 at VIc's house). So really, we're left wondering, and we might not even find out in this next update. I think Ocean can't keep drawing that tension out (of not knowing what the situation is between Nika and Nami) for much longer though, it'll just keep frustrating people more than the secret is worth to the story.
This is assuming Ocean's not just avoiding answering those questions right now, who knows?