Hi Ale, it's me again!
I found the issue in your code, so let's get to it.
...
<labeled-knob x="300" y="50" label="REVERB" style="linear_bar_vertical" trackForegroundColor="B5FFFFFF" trackBackgroundColor="FF000000" type="float" minValue="0" maxValue="1" value="0.2" textColor="FFFFFFFF" textSize="16" width="80" />
<binding type="effect" level="instrument" position="0" parameter="FX_REVERB_WET_LEVEL" />
...
The labeled-knob and control elements should be closed after the binding, and not within itself. Thats why when you close it with the </labeled-knob> the elements disappear because it results in a code error. Also the binding will not work, because is not "binded" to any element. The expression should look like this:
...
<labeled-knob x="300" y="50" label="REVERB" style="linear_bar_vertical" trackForegroundColor="B5FFFFFF" trackBackgroundColor="FF000000" type="float" minValue="0" maxValue="1" value="0.2" textColor="FFFFFFFF" textSize="16" width="80">
<binding type="effect" level="instrument" position="0" parameter="FX_REVERB_WET_LEVEL"/>
</labeled-knob>
...
So the binding is referred to that labeled-knob. Every labeled-knob should have the same structure
Also, another detail that is not resulting in any error, but it might depending on your code is the " after <group ampVelTrack="1">
...
<groups seqMode="round_robin">
<group ampVelTrack="1">"
<sample path="Samples/Soyuz_Eb2_51_1.wav" rootNote="51" loNote="51" hiNote="51" seqPosition="1" />
<sample path="Samples/Soyuz_Eb2_51_2.wav" rootNote="51" loNote="51" hiNote="51" seqPosition="2" />
...
I'll leave the corrected code in another comment, due to character limitations, so you can copy/paste it and check if it works fine for you!
Hope that helps you!
Stay safe!