The role names sound like they are job positions which can and should be broken down to multiple smaller roles. I guess starting with those 5 roles is not bad. When the time comes, anyone in the circle can break them down further when needed.
I would do a little coaching here as well to make sure that they don't fall back to treating roles as job positions with all the implicit expectations.
This brings me to the accountability portion of your question. If I were in the circle, I would raise an objection based on lack of clarity and implicit expectations. The accountability of finance, IT, etc need to be spelled out for clarity sake. What you think a finance should do may differ from what I think a finance should do.
As for the domain, again, there is lack of clarity here. What exactly is the finance, IT, Admin domains. What I think is their domains may differ completely from what others think. To make it clear, the exact domains need to be spelled out.
Again, a little more coaching on achieving clarity, and not relying on implicit expectations is needed. In fact, it sort of violates the following clause in the Holacracy Constitution, though not directly. By saying the domain is IT (or finance, or whatever), and the accountability is the accountabilities of IT (or finance, or whatever), it is completely relying on implicit expectations from former job positions.
4.1.5 Implicit Expectations Hold No Weight
All of your responsibilities and constraints as a Partner of the Organization are defined in this Constitution, and in the Governance that results from it. No former or implicit expectations or constraints carry any weight or authority, unless a Circle’s Governance explicitly empowers them, or they come from a basic obligation or contractual agreement you personally have to or with the Organization.