Why Gb, Db, and Ab (Cb, sometimes Eb) are not listed as tonal centers

My question has to do with Enharmonic flats like Gb(yet F# is listed) not in mode calculator…your tonal center calculator is the best I’ve ever seen. But i have seen other mode calculators when reaching Ab, Db, Gb, and Cb as Ionian(or tonal center) double flat these notes especially in Locrian, Phrygian, and Aeolian. So this creates a problem as note 2 A than note 3 Bbb are the same tone, and since every note unless indicated by blues major/minor have b5, 5 in progression but diatonic scales or keys cannot repeat the same note. In this case A.(Bbb). So I wonder if when the mode calculator stops at Eb, (yours) it knows that phrygian and locrian will start to complicate things. So is this telling me that instead of trying to figure out Ab, or Gb modes that F# and G# are better and possibly telling me that any double flats render the progression useless unless I switch to the enharmonic sharps to be the tonal center so it makes sense. Please help me!🙂 I’m 39, rediscovering theory that was taught to me 20 years ago the wrong way!