Use of rel="alternate" on multilingual site

Question

I operate an English website handling multilingual content (up to 13 other languages), with a large amount—but not all—of our content translated into those other languages. We use rel="alternate" to link to those other pages which presents 2 scenarios:

• Translation exists: show translated article.
• Translation doesn't exist: show original article, with short placeholder text (i.e. "this is not yet translated").

My question is would we run into duplicate content issues, and be penalised for it, if we use rel="alternate" to link to such untranslated content, even if exists on a different language subdomain (specified in the alternate link)?

Answer 1

Definitely you want to avoid that, if the page doesn't have a translated version simple don't put an hreflang, use the hreflang only with translated pages.

If Google discovers false hreflang tags it will eventually ignore them, try to keep hreflang health as best as possible.

Answer 2

Untranslated pages don't need any kind of alternate or hreflang tags. Those are for pages having their counterparts in another languages. Your rule to go should be: no counterpart == no alternate/hreflang.