Mikolaj, every gap between the current reality and a potential you sense is a Tension. In the Tactical meeting (art 4.2.3(e)) you see that we triage the Tensions that are on the agenda that has been build.
You can express a Tension that is Tactical that comes from an Accountability of one of your roles (Governance).
For example: in my role "Speechmaker", where I have the Accountability to represent the organization and talk about Holacracy, I have the Tension that often their is no good sound installation on the venue's where I come. Therefore I want a Next action from the Role "Stuff we Need" to buy a portable speaker set for me.
So in both Tactical as Governance we process Tensions but also outside of these meetings you can express and process Tensions with other Roles.
Hope this helps.