I'm trying to migrate two user fields in Drupal 7 (name in two languajes) to a translated field in Drupal 8.
I have tried several options but all failed.
I have two yml templates (one for the user and another for the translation with parameter translations:true) but not working. 
The user is migrated correctly.
The translation of the user is created correctly.
The field of the user is correctly but the translated field is not translated.

These are a part of the yml files...

migrate_D7_user.yml

>     source:
>       plugin: d7_user
>     process:
>       uid:
>         -
>           plugin: get
>           source: uid
>       name:
>         -
>           plugin: get
>           source: name_english
>       langcode:
>         -
>           plugin: default_value
>           default_value: en
>     destination:
>       plugin: 'entity:user'


migrate_D7_user_translation.yml

>     source:
>       plugin: d7_user
>       translations: true
>     process:
>       uid:
>         -
>           plugin: migration
>           source: uid
>           migration: migrate_d7_user
>       name:
>         -
>           plugin: get
>           source: name_spanish
>       langcode:
>         -
>           plugin: default_value
>           default_value: es
> 
>     destination:
>       plugin: 'entity:user'
>       translations: true

Thank you in advance,
Juanjo.