This is to load wpresidence/languages folder in child theme.
The pins modification in child theme – we didn’t get the instructions from Wpml about that being possible.
As for wpml-config.xml in child theme – all there is as documentation (at least what i found) is here https://wpml.org/documentation/support/language-configuration-files/
The pins modifications can stay in main theme because you create new names. A theme update done via FTP (by simply overwriting theme files) would continue to have the files after update because the names are unique.
Update via FTP video tutorial is here – http://help.wpresidence.net/#!/updatetheme