Copying pages into a new PDF is a useful recovery path, but page count alone cannot establish that the document was fully preserved. Document-level features such as an outline or the form catalog deserve separate checks from whether the page tree can be loaded and saved.

I would keep a fixture with ordinary pages plus those features, then report which survived reconstruction. The output could be a successful page recovery with feature-loss warnings rather than an unconditional repair guarantee. Preserving the original bytes alongside that report would also let a downstream workflow decide whether the recovered document is sufficient for its purpose.