Hi,
I do some localisation in the admin interface, i. e. a previously defined CalendarDateField which is labled <Date>.
In my ArticlePage.php I have something like that:
$fields->addFieldToTab('Root.Content.Main', new CalendarDateField('Date', _t('ArticlePage.DATE', 'Date')), 'Content');

in de_DE.php I added this entry:
$lang['de_DE']['ArticlePage']['DATE'] = 'Publikationsdatum';

The result is like expected: The label changed to <Publikationsdatum>. So far so good.

My question is concerning a future update of SilverStripe. Am I right, that SS will override my personal translations when doing it that way?

Question 2: Is there a recommended way to do this to avoid this kind of thing?

Thanks for your help.

Just keep a copy of your de_DE.php page handy and you should be OK. You will have to replace the file once an upgrade overwrites it though.

Changes like this, if they are universally needed, should likely be submitted to the codebase:
http://doc.silverstripe.org/doku.php?id=translation

Well thanks for your comment, but this is definitivly not solving the problem.

Anybody else interested in this topic should have a look at this very interesting article at

http://www.ssbits.com/overriding-silverstripes-language-files-with-your-own/

It covers the way SS is searching for language files and comes up with a solution for avoiding your translation being overridden by any update in a css-cascading-style manner.

Worth reading.