Yes, this is probably the most sensible approach.

Other options would be to ignore everything you don't recognize or ignore all nodes of the form:

  unrecognized tag [value]

i.e. where you don't recognize the key and the value is not complex.

You could still display stuff like:

  unrecognized tag [
    [text]
    ...
  ]

i.e. text nodes which are children of unrecognized elements.

But approaches like these would need a good justification.