Here is code to copy the form when creating a new language.
Add the following function in userforms/code/UserDefinedForm.php
function createTranslation($locale) {
$page = parent::createTranslation($locale);
$newPage = $page->getTranslation(Translatable::default_locale());
foreach($newPage->Fields() as $field) {
$newField = $field->duplicate();
$newField->ParentID = $page->ID;
$newField->write();
}
foreach($newPage->EmailRecipients() as $recipient) {
$newER = $recipient->duplicate();
$newER->FormID = $page->ID;
$newER->write();
}
return $page;
}
After this has been added you can create new languages on a page and it should copy your form over.