@Jay
Your IR file names must be strings. That mean they must be in quotes ""
const var convol = ["MediumLight", "MediumDark", "MediumSlap", "MediumVox"];
getItemText is only for combo boxes (check the API documentation) so this code will never work.
ConvolutionReverb1.setFile("{PROJECT_FOLDER}"+ control.getItemText() + ".wav")(convol[value]);
What you want is something more like...
ConvolutionReverb1.setFile("{PROJECT_FOLDER}" + convol[value] + ".wav");