I'm a multilanguage guy, you might allready know that Living in a multilang environment, I use on daily basis at least 3 languages, and I have contributed to internationalization of many open source (and not only) software packages - so naturally I am in the multilanguage site development from the start.
Frankly, the feature wich made me curious and finally get me into the large crowd of Mambo/Joomla users was the ease to produce multilingual sites. From that point Joomla (and along with that my skills) have evolved a lot. Now building multilingual sites is a breeze. One of problems from the start with Mambo/Joomla was not the adding the multilingual content and to manage it, but the language files associated with various components. These where often poor quality translations, even missing lot of times, and you need to have an in-depth knowledge how these language strings where implemented to be able to change or tweak them.
Over years various solutions to ease this where implemented, but only with arrival of 1.7+ Joomla a serious tool was implemented in the core.
Yea, you might be already guessed, I'm talking about the Language Overrides tool available from Joomla's Language manager.
The beauty of this tool is that you don't need to touch the available language files, and when you upgrade your language files, your previous tweaks won't be lost.
If you notice language strings that are not appropriate to your website you can change them in Extensions -> Language Manager -> Overrides.
A language string is composed of two parts: a specific language constant and its value.
For example, in the string:
COM_CONTENT_READ_MORE="Read more: "
'COM_CONTENT_READ_MORE' is the constant and 'Read more: ' is the value in the above example.
You have to use the specific language constant in order to create an override of the value. In the newly available interface you can search for the constant or the value you want to change with the search field provided.
By clicking on the desired result the correct constant will automatically be inserted into the form. You don't have anything else to do, "just" to replace the existing string with the desired one, and click "Save".