Hi @rkmoonak,
It is really a bad idea to edit the core theme files. You will loose all the edited codes in next update. If you want to customize anything in the theme, then use child theme. For detailed instructions of child theme, you can visit this link.
Now, for the code, use add the following function in your child theme’s function.php
file
/* Replacing Taxes with Service Fee */
function my_em_text_rewrites($translation, $orig, $domain) {
str_replace('Service Fee','Taxes', $translation);
return $translation;
}
add_filter ( 'gettext', 'my_em_text_rewrites', 1, 3 );
If this does not work, you will need to contact the plugin’s support as this is not in the theme scope.