Categories and Tags: translation not displayed in frontend

It seems that translation of categories and tangs is not displayed in the front-end.
For example, the category widget in the sidebar doesn't display translation for the category corresponding to selected language while post content is correct, but the master language.
Also tags are dispalyed at hte bottom of the post for just the master languange but are missing in the corresponding translations.

Reproduce the issue by selecting a translated language, then inspect how the sidebar category widget and the post's bottom tag list obtain their labels. Done means translated category and tag names appear for each corresponding post language while the post content remains correctly translated.

Written by the indexing model from the issue text.