Interesting, I had done the same thing before, but nothing was added to the menu, and it didn't work properly. But it worked with your code! I must have made a mistake somewhere.

<record id="action_cancel_form_link" model="ir.actions.server">
<field name="name">Cancel</field>
<field name="model_id" ref="termin.model_anlage"/>
<field name="binding_model_id" ref="termin.model_anlage"/>
<field name="state">code</field>
<field name="code">
if records:
for rec in records:
rec.cancel_link()
</field>
</record>

Thankful.