We recently changed Grade & Grades to Score & Scores in the en_utf8. First we changed these in Grades.php and after saving received a message that there were two missing strings. Following the links it indicated that Grade and Grades was missing. When we changed the two strings back, the message went away.

We also changed the two strings in moodle.php. upon saving we received the message that there were four missing strings. Two of them were of course Grade & Grades. The other two led to:

0
firstdayofweek

The field next to it has a 0 in it. So it is not missing.

The other field is:

<< TRANSLATORS: If your language has a Parent Language that Moodle should use when strings are missing from your language pack, then specify the code for it here. If you leave this blank then English will be used. Example: nl >>
parentlanguage

This field is blank, but according to the instructions it should be since we are using English.

Reverting back to Grade & Grades still gives message that there are two missing strings.

However, leaving the modification to Score & Scores, does properly display in the course.