To be honest, If I didn't have the standalone client running on a separate machine monitoring just the basic groups I use for my stream, I wouldn't have realized it.You explained it perfectly. On the TTC system I've always wondered if TTT is supposed to switch to another active slot or not so I'm looking forward to seeing an answer to your question too.
The thing, is I'm also running your version of the Tetra Demodulator on a separate system, standalone without TTT plugin, and it switches to the other active timeslots instantly, without any timeout issues, just like the original russian plugin did. I have it running side by side, that's how I noticed the difference.TTT is design to follow a call in it's entirety (call setup to call release) across the network. (To any carrier belonging to current MNC)
The old plug-in does not do this, which is why this fork of the plug-in and TTT exists.