Nope, but at least, they aren’t lost. They are just there, ready to be made available by the potential successor of Sci-Hub. That’s what matters.

It's not too hard to find the article's doi (programatically) for newer articles. Once you have the doi you have all the important article metadata like author, publish date, etc. I imagine this is all that's required to make the articles searchable.

However, this is certainly more challenging for older articles.