By missing you mean disabled, and by appears you mean enabled...?

Where is your geographic location (in which country/state do you drive your C5)...? Do you drive it on the street...?

Do you have EVAP system physically present...?

What about AC...?

Did you recently get your transmission rebuilt...? Did they edit the tune ahead of the dyno tuner...?

You could ask the dyno tuner if he had specific reasons for disabling or enabling those particular DTC's.