Utter midi confusion

apologies in advance- my setup is such that I cannot be online and have ardour open at the same time.
I have a song with 5 or 6 audio tracks. everything is perfectly lined up and in sync to 170bpm. I then added a midi drum track with no plugin and recorded the midi output of my roland td20 to this track. while recording, I monitored the output of my scarlett thru the td20’s audio input which let me hear my audio tracks, the metronome, and allowed me to play with (practically) zero latency by hearing only the roland sounds. so far so good.
I then added superior drummer to the midi track and played back- everything was fine. sd2 was triggered, everything was in sync.
now the problems started. because I made a few mistakes, I wanted to punch in and record drums over the bad section when I lost my timing and had to regroup.
but to record while triggering sd2 meant enormous latency. too distracting and absolutely unplayable. so I said, I’ll just monitor the roland sounds again. this does not work.
I can see activity on the track- midi data is playing and the meter is displaying that- but there is no sound. when I strike a pad, the meter reflects that. when I record, the midi note is there. but no sound.
drums can only be heard on playback when I allow the midi to trigger sd2. the td20 is putting out the sound I am playing, but the recorded midi does not get anything out of the td20.
in the ?midi/audio config panel? (again, I’m not in ardour right now) there is setting for audio hardware and midi. my scarlett is set for audio. but midi only allows me to choose either “none” or “winmme.” when I choose “winmme” I can hear drums but they aren’t the roland or sd2- the sound comes out of my laptop speakers.
I’m at a complete loss.