Let me illustrate this with a specific example - We're experiencing that Cross Link between HolacracyOne and iGi (even if iGi is powered by Holacracy since 2010, I think the same reasoning applies for a Linked Entity that would not be using Holacracy).
In H1 GCC, there is a Policy that invites Cross Links from Licensees - see https://glassfrog.holacracy.org/policies/1389 - Note that such policy allows for adding accountabilities per governance on the Cross Link Role (this has already happened several times, see our Cross Link Role https://glassfrog.holacracy.org/roles/22016)
Note also that the policy specifies "This Cross Link shall be established upon request of the Licensee and acceptance of these additional terms" which means this Cross Link with such "add an accountability" function, has to be accepted on the first place by the Source Entity being invited to link.
Now, the Linked Entity is still a sovereign entity - the Cross Link Role may object during governance to any proposal adding an accountability that would causes harm to the Linked Entity.
Hope this helps.