I’ve honestly always been confused about this too. It’s not possible to enter the written pitch of octave transposing instruments by playing that written pitch on a MIDI keyboard is it? For example if a want to input a written G3 in the Bass, I have to play a G2 (the sounding pitch) on my MIDI keyboard. By contrast if I want a written C5 in a Tenor Sax part, I can simply play a C5 on my MIDI keyboard when I’m viewing the transposed score.
Why can I input written pitches if I’m inputting into an instrument that is written a 9th above concert, but not one an 8th above? If I want a written G3 in the bass, I’d much rather play the written pitch just like I do for every other instrument that transposes at an interval other than an octave when viewing a transposed score. (Or is there some setting for this that I’ve been missing for years?)