Non-Space Age
Looks like whenever there are multiple surfaces, the combinator displays all of them, making it unusable as a clock.
Currently noticed due to how Factorissimo works. There are 3 surfaces on Nauvis currently, 'Nauvis', 'Nauvis-factory-floor', which freezes at 12 when you research factory lighting (this alone would be easy enough to compensate for) and 'factory-travel-surface'. the last one is dynamic but seems to tick about 15% faster, making it unable to be compensated for with other combinators short of making a matching analog clock and subtracting that from the clock combinator, but at that point whats the point.
I do not know if this is an issue once you go to other planets and start generating other surfaces, but looking at the lua it potentially is.
Seems like people mostly just use this to mess with the time, so I understand if this isn't a big priority.