open plugins on an audio or aux track

Alright - this script will add the EQ3 7-Band plugin to the available insert that you select in the popup dialog.

var pluginPath = [
    'plug-in',
    'EQ',
    'EQ3 7-Band*'
];

var freeInsertButtonIndices = sf.ui.proTools.selectedTrack.insertButtons.map(function (btn, i) {
    return (btn.invalidate().value.value === 'unassigned') ? i : -1;
}).filter(function (i) { return i >= 0; });

var index = Number(sf.interaction.selectFromList({
    items: freeInsertButtonIndices.map(function(i){ return "Insert " + (i+1) }),
    prompt: "Which insert slot do you want to insert the plugin on?",
    title: "Insert plugin"
}).list[0].match(/(\d+)$/)[1]) - 1;

sf.ui.proTools.appActivateMainWindow();

var insertBtn = sf.ui.proTools.selectedTrack.insertButtons[index];
insertBtn.popupMenuSelect({
    menuPath: pluginPath,
    useWildcards: true,
});

Changed the code as you suggested. In addition I also tried to add "(stereo)" behid the EQ3 7-Band because that's how it is showed in the list. Unfortunately in both cases no success. Any ideas?