HTML Export Question

You can publish your file for web, upload it to a server and then use an iframe to embed it to your home grown authoring tool (assuming that's possible in the other tool).

I used to do some consulting with some NGOs and they have a home grown tool. What I found was the time it tooo to jimmy-rig, workaround, and fix issues cost more than the license of a more robust authoring solution. And the more robust solution opened up possibilities that the organization could never consider with their homegrown solution.