Non-existent title?

I’m trying to unlock the player title suffix “Eterno” (Portuguese).
It appears in my title list, but it is locked.
In the English client, there is no suffix named “Eternal”.
I checked every remaining Challenge that rewards player titles, and none rewards “Eterno/Eternal”.
I have 96% of all Challenges completed.
Does anyone know which Challenge unlocks this title, or is it a localization bug?

Unfortunately, this is a known localization bug in the Portuguese client of Diablo IV.

The title suffix “Eterno” does not correspond to an English suffix named “Eternal”. Instead, it is a translation error where the Portuguese localizers accidentally translated the backend tag for standard “Eternal Realm” characters, rather than mapping it to the actual gameplay reward title.

Because it is a UI ghost entry bound to a realm flag rather than a Challenge achievement, it has no unlock triggers and cannot be obtained by completing standard game content. You can safely skip it, as it will not prevent you from reaching 100% completion on your actual Challenge achievements.

Sorry about that also. “Eterno/Eternal” is honestly a very cool player title to have as a character. Hope Blizzard again will deploy a patch upgrade in order to fix this in Portuguese!

Good luck also to you to complete all the challenges in the game as well! Hope you will get to 100% very soon! You can do this!