Just a self-update on this one.  I worked out some Javascript that inserts a new line after the code is executed in Chrome's developer console.  I plan on figuring out how to insert this code into one of the Web Screen JS files but not a high priority so might take me a while to get back to this.  Meanwhile, as a workaround, you can install the Tampermonkey Chrome Extension and setup this script to execute on Sage 300 Web Screens allowing it to work consistently.  I've also found I can insert additional scripts to map keys to all sort of elements - just use this as a base:

document.addEventListener('keydown', function (event) {
  if (event.code === 'Insert') {
    var button = document.getElementById("btnAddDetail");
    if (button) {
      button.click();
    }
  }
});