I tried this version. It seems to be the same as on the jack…org/download page, right? It seems to work as far as your use case is concerned (started your radium and it seems to connect to that jack server). The ltc-tools (with jltcdump as I mentioned in another mail in this thread). Does not seem to be compatible with this version of jack though. I get the same “failed to connect errors” as before.
unknown option character l
connect(2) call to jackdmp 1.9.11/jack-502/default/jack_0 failed (err=No such file or directory)
So, it seems like Jack2 works in some ways (as in your use case) but perhaps that the tools that link to its dynamic libraries are not always fully compatible. Or that the programming interface between jack1 and jack2 has changed over time, I don’t know.