TYPO3 Core

DataHandler line 4107: copyRecord_processInline()

4125: // If language is set and differs from original record, this isn't a copy action but a localization of our parent/ancestor:
4126: if ($language > 0 && BackendUtility::isTableLocalizable($table) && $language != $row[$GLOBALS['TCA'][$table]['ctrl']['languageField']]) {
4127:     // Children should be localized when the parent gets localized the first time, just do it:
4128:     $newId = $this->localize($v['table'], $v['id'], $language);
4129: }

In line 4126 it is checked if the parent but not the child table is localizable.
This leads to the following problem:
If you try to localize a record e.g. a download(localizable) which holds multiple downloadfiles(table is not localizable), an error is thrown that says :
'1: Localization failed; "languageField" and "transOrigPointerField" must be defined for the table ...'