Hi!
Transform from Centroid is an alias that uses the Transform SOP with specific parameter values. Therefore, it won't appear in the library for adding to a radial menu.
Instead, you'll need to use a Script Action, which you can find under the Utilities tab.
Set the label to "Transform from Centroid" and choose an icon. Then, in the script section, add the following script:
import soptoolutils
node = soptoolutils.genericTool(kwargs, 'xform', exact_node_type=False)
node.setParmExpressions({
'px': 'centroid(0, D_X)',
'py': 'centroid(0, D_Y)',
'pz': 'centroid(0, D_Z)'
})
node.setName('transform_from_centroid1', True)
I've attached an image as well.
Let me know if that works for you.