New users are created with the UI language settings of the Organization as default.
Available workaround (if any):
They can be sent a direct link to the 'Language' setup page (https://cloud.memsource.com/web/setup/localeSettings).
A new option on the 'Create User' page to change the UI language (see screenshot). The default value may be the Organization's language or 'English (US)'.
Similarly, a new column could be added to the 'userImport....xlsx' sample file and be processed on importing users in bulk.
New users may find it difficult to navigate to the 'Language' setup page in a UI shown in a completely unknown language.