With the p2g_launch_presentation_locale you can control the LTI language. Many LTI tool consumers push the application locale to the LTI tool provider.
When the learner changed the course language into e.g. Dutch, the LMS will tell Presentations2Go to use locale NL-NL.
However, in case you want to overrule the language, you can force the language with this custom parameter.
Be aware the language you select must be available in Presentations2Go too.
if you do not use this custom parameter the default behavior will be adapting the tool provider language.