What are you using to translate the text with? Based upon the current code:
https://themes.trac.wordpress.org/browser/twentyfourteen/2.6/comments.php#L28
It looks like it should be available for translation
I used poedit. I tried to find the text from the *.po file of the theme and from the *.po file of WordPress itself. I didn’t find the text “thoughts on” from those files.
if ( ‘1’ === $comments_number ) {
29 /* translators: %s: post title */
30 printf( _x( ‘One thought on “%s”’, ‘comments title’, ‘twentyfourteen’ ), get_the_title() );
31 } else {
32 printf(
33 /* translators: 1: number of comments, 2: post title */
34 _nx(
35 ‘%1$s thought on “%2$s”’,
36 ‘%1$s thoughts on “%2$s”’,
37 $comments_number,
38 ‘comments title’,
39 ‘twentyfourteen’
40 ),
41 number_format_i18n( $comments_number ),
42 get_the_title()
43 );
44 }
All ” thought on”, “thoughts on” should be translatable.
Maybe I should add missing item to the translation? But how to add an item to the po-file? There is no option for that. Of course I can hadcode those, but I must repeat it in every update.
How I can translate items, which I don’t see in *.po file.
I can’t add to the po-file any new item. I would need perfect twentyfourteen.pot, which has everything, including ‘%1$s thought on “%2$s’ etc.
I added manually to a po-file missing translations and converted then it to a mo-file. But I didn’t get texts translated. I just must alter the source code :(.