AdaptView.addChildren handles subviews / children for Pages, Articles, Blocks (not Components), it isn't meant for use elsewhere.
If you're using a recent version of the framework, it may be easier for you to use jsx for rendering rather than handlebars.
Here are some fabulous examples from the community, https://github.com/nachocinalli/
mcq, gmcq, accordion etc have jsx versions.
Otherwise, the code you posted above should work just fine.