That seems surprising to me. I don't remember trying to embed bitmap images in SVGs in Hype. However, straight HTML can be pasted in an element. I don't see why Hype would care. Although, I didn't test it.
Yes, I have seen cross-browser issues with SVG. When I use SVG as a background image in an element, the image doesn't always scale proportionally. It depends on the browser. On the projects that I've been working on, this isn't a major issue.
SVG is a bit bleeding edge. For web projects, it's tough to fix the problems. For the app projects, focusing on just iOS is easier.
But as mentioned in another thread, I think the right way to fix this problem is to leverage the matter.js "view" option. Unfortunately, Tumult currently has the API on lockdown.