You copied wrong code
you need to copy rendered item data from /module-sales/view/adminhtml/templates/order/view/items/renderer/default.phtml
<?php $_item = $block->getItem()
$block->setPriceDataObject($_item) ?><tr>
<?php $i = 0;
$columns = $block->getColumns();
$lastItemNumber = count($columns) ?>
<?php foreach ($columns as $columnName => $columnClass):?>
<?php $i++; ?>
<td class="<?php echo /* @noEscape */ $columnClass?><?php /* @noEscape */ echo ($i === $lastItemNumber ? ' last' : '')?>"><?php /* @escapeNotVerified */ echo $block->getColumnHtml($_item, $columnName) ?></td>
<?php endforeach; ?></tr>
get item with column name, will allow you to get product name.