In GlassFrog v4.1 you cannot add/edit the Lead Link's accountabilities.
The reason behind this is that a circle’s Lead Link inherits the purpose and any accountabilities from the circle itself, and controls any domains defined on the circle, just as if the circle were only a role and the Lead Link filled that role.
In practice, the Lead Link's specific accountabilities can be deferred to another role, but GlassFrog doesn't have the capability to show that, so those will remain in the Lead Link's accountabilities list.
For reference, here is Article 2.2.3 of the Holacracy Constitution (version 4.1):