Hello,
You can use the align attribute, but note that if you don't set a width for a table, it fits the whole page.
This sample is tested and working with MS Word and LibreOffice:
$html = '<table border="1" width="400" align="left">
<tbody>
<tr width="400">
<td style="background-color: yellow">1_1</td>
<td rowspan="3" colspan="2">1_2</td>
</tr>
<tr width="400">
<td>Some random text.</td>
</tr>
<tr width="400">
<td>
<ul>
<li>One</li>
<li>Two <b>and a half</b></li>
</ul>
</td>
</tr>
<tr width="400">
<td>3_2</td>
<td>3_3</td>
<td>3_3</td>
</tr>
</tbody>
</table>';
$docx->embedHTML($html);
$html = '<table border="1" width="400" align="right">
<tbody>
<tr width="600">
<td style="background-color: yellow">1_1</td>
<td rowspan="3" colspan="2">1_2</td>
</tr>
<tr width="600">
<td>Some random text.</td>
</tr>
<tr width="600">
<td>
<ul>
<li>One</li>
<li>Two <b>and a half</b></li>
</ul>
</td>
</tr>
<tr width="600">
<td>3_2</td>
<td>3_3</td>
<td>3_3</td>
</tr>
</tbody>
</table>';
$docx->embedHTML($html);
If you need to set the cell alignments, then you need to set td tags align, not the table tag.
Regards.