I don’t think these do as just temporary, but would be good if Castle St does get fully pedestrianised if they did something more permanent with covers, as the pavement there is well big enough to have that and would mean they can be all year round.
I guess there are two options if the street were indeed to be 'fully pedestrianised'.
Either you'd have the current road as the seating area and the current pavements as the 'walkway', and have a central dining area with awnings running down the middle, or you'd have more like up on the Liverpool One terrace, where you've got awnings extending out from the restaurants themselves with large seating areas spilling out towards the current road (which would become the walkway).
I quite like the idea of the former personally, but our weather probably lends itself more towards the latter (food remains under awnings even when being brought to the table).