For such an old software this should have been addressed since long. As well as easing automation editing (you can't currently copy the data from one lane to another). Or a specific selection tool for automation lanes (at the moment selecting areas selects all the points, when I only want to remove some specific ones). Compared to the huge advance and technicity of nowadays audio/midi softwares, Vegas and consorts appears completely abandonned or archaic in that domain.
I've just tried using @jetdv's method. Media event length 10 seconds, keyframe every 2 seconds, Ctrl+drag to make the event 5 seconds, keyframes are now every 1 second. They keep their relative positions. Is that the type of result you want?