I'm not sure how to fix tracking points manually AFTER setting the information to the null and then parenting the null to the text. I've tried changing the values numerically but it doesn't do anything, and by looking at the tracking points on the image, they don't look particularly off.
The biggest issue is that I'm trying to have an object come on screen halfway into the shot and the exit screen, tracked with another object (for example, say I had a pan across a keyboard, the letter D was on screen for maybe half the shot, and I wanted to put a word next to the letter D, so it starts off screen, comes in with the letter, and exits screen with the letter). This seems easy enough, but it always idles on screen before the tracking point appears for some reason. I tried tracking to a few different points that come on and off screen at different times, and then lining them up, and that helps, but the text still appears on screen before it should and I can't figure out why.
I've tried finding a Mocha tutorial, too, but every tutorial is for an object that is always on screen and never exits, and adding something that stays on screen.
Here's the video. I'd like to put text next to the stereo, which starts and ends out of frame, and remove the security system logo.
I always try to track something else in the shot even if it is on a different plane until the object comes on screen. After I get the initial track of the object I move my tracking spline to another object that stays on screen and track it backwards or forwards frame by frame. This usually does the trick because you just want the basic motion of the camera while the object is coming/going offscreen.
You can also just parent the tracking null to another null then manually keyframe the position of this "FIX" null for the few frames that it comes and goes. But I do this less often because it's hard to get the motion just right.