How to "themeify" stuff from functions.php in child theme?

How to localize theme when functions.php can't be copied to child theme (white page, WP dies), and I cant copy the function that needs translation (white page, WP dies)?

The function in my example are "the_excerpt_feature" that prints "Read More" that I want to translate....

Hopefully its just me that don't understand how to do things... any ideas?