That's not a CPU, it's a simple circuit. From the article, "Simple superconducting logic circuits have been shown to operate at speeds of up to 770 gigahertz."
Exotic semiconductor transistors can switch that fast, record being over 800GHz I think. Regular transistors of the type in your phone can probably do around 200-300GHz. Not to say there could not be revolutionary designs opened up with superconducting wires or switches, just the switching speed itself doesn't necessarily tell us one way or the other.
Actually it's probably more like 200 than 300, I haven't seen 3nm models but transistors are still getting faster.
I'd be interested to know from any experts whether there is potential for fundamentally higher switching speed in super conducting circuits. As you suggest, they are not necessarily directly indicative of the clock speed of a specific real world circuit or CPU, especially considering super conductors don't even use transistors and need to use different building blocks for equivalent logic... but as a rough indication based on order of magnitude of switching speed would be interesting.
Super conducting CPUs already exist (at below room temp), and they don't use semiconductors. They don't have an exact transistor equivalent but use digital logic circuits such as Quantum Flux Parametron (QFP) and rapid single flux quantum (RSFQ), which are comprised of Josephson Junctions [0].
I have a limited understanding of this technology, but it appears the only material required to build a Josephson Junction is the super conductor itself. Relying on quantum effects of a gap between two conductors rather than specific material properties. Which explains how the entire digital circuit of a CPU can be (and has been) made super conducting.
So while it is true that CMOS are limited by the resistance of both the conductor interconnects AND the semiconductors. Super conducting circuits only need a conductor... There are of course various other drawbacks, including feature size due to the nature of super conducting materials, but this is offset by huge advantages not only in power efficiency and lower heat generation (only as required by landauer limit), but secondary effects such as being able to drive them almost into the THz arena [1]
[0] https://en.wikipedia.org/wiki/Josephson_effect
[1] https://spectrum.ieee.org/superconductor-logic-goes-lowpower