We have just created a HubSpot APP called Analytics Amplifier that will also help you do this + push offline events to Google Analytics when they happen.
I've noticed that GA doesn't detect the latest CTA I've integrated on an external page. I've used the same method than before wich was working well but now when we click on the CTA, no event is detected by GA.
And hubspot doesn't seem to detect the CTA is used in an external web page, not even seen or clicked.