UTC would save you w.r.t. timezones, but it still has leap seconds and the like to adjust for nonuniformities in the earth’s rotation (around itself and the sun).
However, these jurisdictions change timezones in autumn and spring, so specifying the current timezone should work just as well as specifying UTC. 01:30:20 CEST is not repeated, nor is 01:30:20 CET.