Overriding TypoScript labels is the way to go. Manually editing l10n files is a very bad idea - these files are overwritten when translations are updated. If the extension receives an update and new shortcuts are added, you will need to perform updates.
Changing the XML files to convert to XLIFF has not changed anything in the best practice that you should use to customize labels to suit your needs. This is just another format with a standardized translation server (Pootle), which (theoretically) allows you to use some special functions, for example, multiple forms.
Conclusion: Use TypoScript.
For the default language (without the config.language set) use:
plugin.tx_felogin_pi1._LOCAL_LANG.default {
key = value
}
For a specific language, for example. German use
plugin.tx_felogin_pi1._LOCAL_LANG.de {
key = value
}
source
share