Steps:
1) Enter in HTML mode:
<ins author="RadEditorUser" command="Insert" timestamp="1635859985945" title="Inserted by RadEditorUser on 11/2/2021, 3:33:05 PM" class="reU0">
<table>
<tbody>
<tr>
<td> text</td>
<td> </td>
<td> </td>
</tr>
<tr>
<td> </td>
<td> text</td>
<td> </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>text </td>
</tr>
</tbody>
</table>
</ins>
2) Select the word in cell 1
3) Apply Bold formatting
<ins author="RadEditorUser" command="Insert" timestamp="1635859985945" title="Inserted by RadEditorUser on 11/2/2021, 3:33:05 PM" class="reU0">
<table>
<tbody>
<tr>
<td> </td>
</tr>
</tbody>
</table>
</ins><ins author="RadEditorUser" command="Insert" timestamp="1635859985945" title="Inserted by RadEditorUser on 11/2/2021, 3:33:05 PM" class="reU0">
<table>
<tbody>
<tr>
<td><strong author="RadEditorUser" command="Bold" timestamp="1635860413199" title="Formatted by RadEditorUser on 11/2/2021, 3:40:13 PM" class="reFormat reU0">text</strong></td>
</tr>
</tbody>
</table>
</ins><ins author="RadEditorUser" command="Insert" timestamp="1635859985945" title="Inserted by RadEditorUser on 11/2/2021, 3:33:05 PM" class="reU0">
<table>
<tbody>
<tr>
<td></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td> </td>
<td> text</td>
<td> </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>text </td>
</tr>
</tbody>
</table>
</ins>