Aug 26
10
Google’s Gary Illyes said that hreflang alternates, hreflang URLs are not “indexed in the proper sense.” In short, Google just keeps the hreflang URL as alternate URLs. So the URL is not what is getting the page indexed, it is just being stores as an alternative to the main page URL.
The rest is here:
Google: Hreflang URLs Not Indexed In The Proper Sense