[Joshua Pearson] “However, when i want to do something really simple to the audio of a video clip WITHOUT detaching it, like cut a piece of room tone in over an off-camera cough or interviewer voice, it is not obvious how to do such a simple thing…”
Have you tried copying a portion and pasting as Connected?
Ive done this both ways where I pasted as Connected in Project and within the clip itself using “Open in Timeline” option.