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That is technically an error. If a page or post doesn't exist in a certain language, hreflangs pointing to it (from other pages) shouldn't exist. When the post is published, then the hreflangs should be written. It's probably not going to destroy your sites rankings by itself, but in SEO, the second you start making concessions on one front - people argue that you should make more concessions in other areas. Before you know it, you have a big tangle of loads of different errors. Optimisation, is about making things 'optimum'. It's not optimum to have hreflang errors like that