I am also new to programming and spent a lot of time trying to find where I could translate this text.
But after I understood, I found it very easy (but really easy!).
You simply enter buddypress/bp-core/bp-core-template.php
Find the word salutation, or go to the end of the content.
This text is linked to the bp_email_get_salutation function
Just replace the lines:
_x( 'Hi,', 'Unnamed recipient salutation', 'buddypress' )
_x( 'Hi %s,', 'Named recipient salutation', 'buddypress' )
by the words that your language.
I think by the time of your post I won’t be able to help you, but I hope I can help other people with the same difficulty we had.