Figured it out! Sneaky little issue. :ph34r:
Reproduction steps:
Select Silent Battle Timer
Run WoT - Go into Training (the tutorial)
Timer is silent.
Now...
Select Silent Battle Timer
Select, under WoT Tweaks, "Preload Sounds"
Run WoT - Go into Training (the tutorial)
Timer is ticking.
Something in the Preload Sounds mod makes it load sounds from the normal audio folder, and not the res_mods one.
(Preload Sounds generates the "engine_config.xml" thingie.
Possible fix/solution:
<project>
<name>GUI</name>
<preload>true</preload>
</project>
If the installer detects selecting both Silent Battle Timer, and Preload Sounds, make Preload Sounds have this instead:
<project>
<name>GUI</name>
<preload>false</preload>
</project>
And then....
Select Silent Battle Timer
Select, under WoT Tweaks, "Preload Sounds"
Edit "engine_config.xml", changing the code bits above to "false"
Run WoT - Go into Training (the tutorial)
Timer is silent.
(The GUI files total less than 4 MB data.. so it shouldn't affect performance in any noticeable way..) ^_^