They claim 75% efficiency AC-AC [0], and they point out that there’s no degradation with time. What estimates are you using to arrive at the 25% figure?
i didn't do any math tbh, i just took the 25% number from the wikipedia page for cryogenic energy storage. i assumed their efficiency would be lower of the smaller temperature differential, but maybe it will be higher because they are storing part of the energy as pressure rather than temperature
[0] https://energydome.com/co2-battery/