How localization works

At startup, Macrium Reflect loads the language .xml file corresponding the chosen language in 'Other tasks' > 'Edit Defaults and Settings' > 'Advanced' > 'Language':

Folder 'C:\program Files\Macrium\Common\Languages' is the source for all available languages and translations.
New languages are automatically downloaded when Reflect starts.  

Language files are named using the ISO 639-1 character code of the language.

Example xml format:

<localization>
    <language code="de" updated="2021-11-12T15:18:15+0000">German</language>
    <date_created>19/11/2021 11:48</date_created>
    <executable>
        <name>ReflectBin</name>
        <strings>
                <IDR_MAINFRAME-POPUP1>&amp;Datei</IDR_MAINFRAME-POPUP1>

• The language code must be a valid ISO 639- code, in this case it's "de"
• The updated date of "2021-11-12T15:18:15+0000" indicates whether the file is outdated, and if so, it will be replaced if a later file is found when checking for updates or if the language is switched to German.
• The executable name "ReflectBin" indicates that the text is used in the main Reflect application. 
• In the example above term IDR_MAINFRAME-POPUP1 is a unique identifier (term) that defines the text element Datei in Macrium Reflect, in this case it's the first menu item on the main screen: