Exactly word "probably" is a deal breaker in this case. I am also curious how someone was thinking JS will be a good idea for such project. But hey, there are people building cars out of plastic bottles...
It seems like you have to wait some seconds for the server to process the comment, if you refresh it should let you comment again. Anyway, looking forward to the data release, through a blog post I suppose?
I'm always baffled why people choose JS over Erlang/Elixir which is designed to do this and comes with the tools/libs required to scale.