Maybe this is already available, but I haven't found it.

I would like to be able to select a section of the song and hit "transpose," select the semitones, and it would only transposes that part of the song. So if I decide I want the last chorus of my song to modulate, I don't have to manually transpose that section of the song. Or if I want to take a modulation out, I can do it with a few clicks instead of redoing every chord manually.

I think the parameter 'section of a song' is the key here. I would do this by Edit, Song Form, Unfold to one big chorus. Then Edit, Transpose, From .. To and complete the info.

I recall something about the Mac version not having this From .. To option of the command; not sure. If I'm right, and you have a Mac, then +1 for your Wishlist item.

I don't know why I never saw this. I have looked at that menu a thousand times, and it never registered that the "from.. to.." was for that. Egg-on-face moment.
Thank you for pointing that out.

We have all been there.

Me many times!