No these words don’t come from wordpress core. They are spefic from SuperMagPro and from “content-author.php”.

This is what I did and it Worked fine:

Downloaded “/wp-content/languages/themes/supermag-el.po” & “/wp-content/languages/themes/supermag-el.mo” files from supermag free theme (not PRO). (Most of PRO theme strings are allready translated there!)

1) Open “/wp-content/languages/themes/supermag-el.po” with text editor
2) Add # "msgid "Written by"msgstr "Συντάκτης:"# "msgid "Website"msgstr "Ιστοσελίδα" at the end of text
4) Save file (from txt editor)
5) Open again “/wp-content/languages/themes/supermag-el.po” this time with Poedit. You should now see this words at the end of all translations…
6) Save file without doing any modifications.
7) Upload to server “/wp-content/languages/themes/”. Keep backup of original files in case something goes wrong.

There you go!! you have added this words and everything is good

Thank you… I just found the solution here:

https://www.acmethemes.com/supports/topic/sub-menu-items-are-coming-up-at-the-top-of-the-menu-instead-of-next-to-parent/

What about my other question.. “Is there a way to show custom taxonomies in theme widgets?”