TYPO3 Core

I have temporary fixed it with a Xclass of IconFactory:

class IconFactory extends \TYPO3\CMS\Core\Imaging\IconFactory
{
    public function mapRecordTypeToIconIdentifier( $table, array $row )
    {
        if( isset( $GLOBALS['TCA'][$table]['ctrl']['typeicon_column'] ) && 
                isset( $GLOBALS['TCA'][$table]['ctrl']['languageField'] ) &&
                isset( $GLOBALS['TCA'][$table]['ctrl']['transOrigPointerField'] ) &&
                $GLOBALS['TCA'][$table]['columns'][$GLOBALS['TCA'][$table]['ctrl']['typeicon_column']]['l10n_mode'] === 'exclude' &&
                isset( $row[$GLOBALS['TCA'][$table]['ctrl']['languageField']] ) && 
                isset( $row[$GLOBALS['TCA'][$table]['ctrl']['transOrigPointerField']] ) ) 
        {
            $sysLanguageUid = $row[$GLOBALS['TCA'][$table]['ctrl']['languageField']];
            $sysLanguageUid = is_array( $sysLanguageUid )? (int)array_shift( $sysLanguageUid ) : (int)$sysLanguageUid;
            if( $sysLanguageUid > 0 )
            {
                $parentUid = $row[$GLOBALS['TCA'][$table]['ctrl']['transOrigPointerField']];
                $parentUid = is_array( $parentUid )? (int)array_shift( $parentUid ) : (int)$parentUid;
                if( $parentUid )
                {
                    $column = $GLOBALS['TCA'][$table]['ctrl']['typeicon_column'];
                    if( $rowDefaultLang = \TYPO3\CMS\Backend\Utility\BackendUtility::getRecord( $table, $parentUid, $column ) )
                    {
                        $row[$column] = $rowDefaultLang[$column];
                    }
                }
            }
        }

        return parent::mapRecordTypeToIconIdentifier( $table, $row );
    }
}

Markus Klein wrote:

I'm not sure where the exact bug really is. Actually the row passed into that function should be "ready" (meaning record overlays applied, etc).
Then the value of the typeicon_column should be correct and exclude-mode needs no extra handling anymore.

Can you elaborate how you use that function?

An example of a TCA configuration could be:

$GLOBALS['TCA']['tx_child'] = array(
    'ctrl' => array(
        'title'    => 'Child',
        'label' => 'typecolumn',
        ...,
        'origUid' => 't3_origuid',
        'languageField' => 'sys_language_uid',
        'transOrigPointerField' => 'l10n_parent',
        'transOrigDiffSourceField' => 'l10n_diffsource',
        'delete' => 'deleted',
        'type' => 'typecolumn',
        'typeicon_column' => 'typecolumn',
        'typeicon_classes' => array(
            '' => 'type-unknown',
            'A' => 'type-a',
            'B' => 'type-b',
            'C' => 'type-c',
        )
    ),
    'columns' => array(
        ...,
        'typecolumn' => array(
            'exclude' => 0,            
            'l10n_mode' => 'exclude',
            'l10n_display' => 'defaultAsReadonly',
            'label' => 'Type',
            'config' => array(
                'type' => 'input',
                'size' => 1,
                'eval' => 'trim'
            ),
        ),
        'parent' => array(
            'config' => array(
                'type' => 'passthrough',
            )
        )
    )
);

$GLOBALS['TCA']['tx_parent'] = array(
    'ctrl' => array(
        'title'    => 'Parent',
        'label' => 'title',
        ...,
        'origUid' => 't3_origuid',
        'languageField' => 'sys_language_uid',
        'transOrigPointerField' => 'l10n_parent',
        'transOrigDiffSourceField' => 'l10n_diffsource',
        'delete' => 'deleted'
    ),
    'columns' => array(
        ...,
        'children' => array(
            'exclude' => 0,
            'label' => 'Children',
            'config' => array(
                'type' => 'inline',
                'foreign_table' => 'tx_child',
                'foreign_field' => 'parent',
                'maxitems'      => 9999,
                'foreign_default_sortby' => 'typecolumn',
                'appearance' => array(
                    'levelLinksPosition' => 'top',
                    'showSynchronizationLink' => 0,
                    'showPossibleLocalizationRecords' => 1,
                    'showAllLocalizationLink' => 1,
                    'expandSingle' => 1,
                    'collapseAll' => 1,
                    'useSortable' => 0,
                    'enabledControls' => array(
                        'info' => 0,
                        'new' => 1,
                        'dragdrop' => 0,
                        'sort' => 0,
                        'hide' => 0,
                        'delete' => 1,
                        'localize' => 1,
                    ),
                ),
                'behaviour' => array(
                    'localizationMode' => 'select',
                    'localizeChildrenAtParentLocalization' => true,
                    'disableMovingChildrenWithParent' => true,
                )
            )
        )
    )
);

The non-localized column typecolumn is used as type. All inline entries of a localized parent has an empty value for typecolumn and the type class will always be type-unknown.