This is the language constant use to translate this.
[gist type="php"]
COM_EASYDISCUSS_BADGES_HISTORY_NEW_POST="Created a new discussion %1s"
COM_EASYDISCUSS_BADGES_HISTORY_NEW_DISCUSSION="Created a new discussion %1s"
[/gist]
You can override these language constants translation from your site backend > extension > language > override .
But once you translated this, it will only affect the new point history, the existing one already stored in database.
If you would like to modify the existing data, you have to manually update this from your database under this table #__discuss_users_history .
Documentation :
https://stackideas.com/docs/easydiscuss/administrators/configuration/creating-language-string-override