(Previously posted to video.stackexchange.com before realizing there are probably few Kdenlive on that site.)

I've been using Kdenlive for a month or so. One of my favorite transitions is a roll transition, where the old clip slides out (e.g. from the center to the left) while at the same time the new clip slides in (e.g. from the right to the center) creating the effect of the old clip being pushed out by the new clip. To do this in Kdenlive, I slightly overlap the two clips in different tracks then apply two Slide transform, one to the old clip (a slide out) and one to the new clip (a slide in). However: 1) this is time consuming; 2) the movement is linear, there isn't a way to a dynamism or speed changes in the movement.

So how to do a better and easier roll transition using Kdenlive?

Try to use a transform effect. First, it has keyframes, and you can use different keyframe interpolation methods.
You can emulate speed changes by using multiple keyframes and changing the position parameters accordingly (e.g. use two keyframes far apart for a small movement and then keyframes closer together for larger movement).