Does this mean that anyone can raise a tension on behalf of the whole circle (even if it's not from one of their current roles) but only the LL can object to it on behalf of the circle as a whole? If so, is this the case for Governance as well as Tactical meetings?
No you can only process a tension in governance on behalf of one of your role. It has to be something limiting one of your roles in some way. In Fred's example, the tension is about the tactical meeting timebox, so it's reasonable to think that any circle member could process it — since every circle member shows up at tactical meetings, they are all impacted by changes made to the process.
There is no objective right or wrong answer as to whether a proposal or an objection is valid: the Facilitator has to test it to find out. If I facilitated, I would ask the objector whether it's impacting her in one of her roles.
If she said something like:
"It impacts all of my roles because I show up at tactical meetings every week. I need more than 30 min to process my items, and I need to make sure others have time to process their items too because I rely on their roles for a bunch of things and need to feel confident they're processing everything they need."
Then she gave me a reasonable argument for why it impacts her roles, and I would chart the objection as valid.
However if she said something like:
"Well it doesn't impact my roles in any way, 30 minutes are enough for me to process my items generally. However, I worry that others may need more time and I want to make sure that they're not feeling rushed."
I might dig a little bit to find out what exactly is her concern about others feeling rushed. If it's really just a general concern for their well-being, then she would have just told me she's not objecting on behalf of her roles, but rather out of concern for the impact it might have on others. That would not be a valid objection. I would further coach her (and the circle) that if others indeed do have an issue with the 30 min timebox, they should raise an objection.
Now if you are in the Lead Link role, your role represents the entire circle so you can process any tension that impacts the circle (whether you're proposing or objecting).
If this is the case, and tensions/proposals are only valid if they are being sensed by an existing role, in cases such as new Holacracy implementations where governance records may be far from optimum, or where the operating environment has changed radically and quickly, meaning internal governance has been rendered inadequate, this restriction may significantly delay the process of quickly finding a new equilibrium. Unless I already have the authority I can't contribute to the circle's ability to discover the need for changes to the way authority is structured. Surely that can't be the way it works? What if I'm sensing the low voltage light and the plane's headed for a potential crash?
Criteria for valid governance proposals in Constitution 4.1 are in article 3.2.2: Criteria for Valid Proposals. It also says:
A Proposal is always valid regardless of the preceding criteria if it is made solely to help evolve the Circle’s Governance to more clearly reflect activity that is already happening, or to trigger a new election for any Elected Role.
In other words, if you're already doing some work not currently captured in governance, you can propose changes to governance to reflect that work (e.g. creating a new role).
If you're sensing something else, then you can always go talk to the Lead Link or any other role you think might resonate with this tension, and suggest that they process it. Or even propose processing it on their behalf if you think you know better how to articulate it; if they give you that permission, you're good to go.
If however 1) they don't resonate with the tension you're sensing, and 2) you're not just trying to capture some governance to reflect work that's already being done, then you're right, you will not be able to process that tension directly in governance. This is meant to protect the circle from people having "great ideas" that are not grounded in actual experience from reality.
Hope that clarifies!