What happens if you use next code in Page - Function and Global Variable Declaration:

(function(){
    $(apex.gPageContext$).on("apexreadyend", function(jQueryEvent) {
        let tbGroup$ = $('#IG_STATIC_ID_ig_toolbar').find('.a-Toolbar-group').last();
        if (tbGroup$.length)
        {
            tbGroup$.addClass('a-IRR-buttons');
        }
        apex.theme42.page.init();
    });     
})();

IG_STATIC_ID to be replaced

your code in "Initialization JavaScript Function" to be disabled

'show maximize button' to be checked on the template options: