I've noticed that most, if not all, cosmology-dependent quantities in the TNG database are given for an h=1 cosmology (e.g. masses are 10^10 M_sun /h). Now the units for StellarPhotometrics are simply listed as 'mag'. So my question is, do these magnitudes correspond to the native TNG h=0.6774 cosmology, or are they mag - 5 log_10 h?
All the little h factors are floating around because they are used in the internal unit system of the code.
But the StellarPhotometrics are coming from interpolating SPS tables (in this case, BC03), so they should be actual magnitudes as you say, without any extra cosmological factors.