In line 16 you set:
<set name="game_log">b3.log
1.: That is not the game log file
2.: It is missing a trailing
</set>Looking at your b3.xml file it seems you are confusing several parts of the installation and configuration.
When it says:
/path/to/b3.log you're supposed to fill in the actual path to where your b3.log file should be created. As a default just
b3.log will probably work just fine.
That also goes for the game_log. You should point it to the logfile that is created by the game. B3 needs to know where your game log is, so it can read from it.