We have looked at this a few times but it is reasonably complex. As you might realize, just replacing a single chord (letter) with the other (Cb to B, A# to Bb etc.) has to take into account II-V-I progressions, any other previous or following transpositions/progressions, the key (or not), and perhaps the transposing instrument.
If it is a specific transpose you use regularly, you can lock the song in that key (song edit>info) and enharmonically change any chords needed (however you might need to have the transposing instrument set to C otherwise it will transpose again.)

We do hope to spend more time on this in the future. Thanks for your thoughts.