It’s a bit of a hack, but I’ve come across quite a few cases where an embed script is just used to create an iframe tag. An easy way to test this is to add the embed script to a non-ember site, for example, try adding it to a WordPress site. You can then look at the HTML that is rendered by the script with your browser’s web inspector. If you see a that an iframe tag is rendered, try adding the value of the iframe’s src to your Discourse allowed iframes site setting.
You should be able to add <iframe src="<your_iframe_src>"></iframe> to your House Ad HTML. You’ll probably need to set height and width attributes on the iframe.