Today I experienced a some what weird behaviour when renaming the default "Title" column of a custom list. Note that im on a german site collection with english as selected menu language. The following steps were taken:
I created a custom list. As you can see, the "Title" field is named "title".
Now I go to the list settings, select the "Title" field and rename it to "title123".
On an english system the title is now displayed as "title123". On the german system the title is shown as "Titel":
Why does this happen? Are there any resource files or something like that to change?