can a behavior be edited after it has been recorded

You can certainly lay new recordings on top. Very common thing to do (unless you are perfect first time every time).

If its just a trigger, you can go to the timeline track recording for triggers, zoom in to make it easier, but right click and it will tell you the available trigger names for that track. You can pick one then stretch it out and move it around doing drag and drop. It starts really small, which is where zooming in helps (so you can grab the edge more reliably).

If a dragger, you can create a new recording over the top of the old recording. It appears as a new layer in the timeline panel. To smooth the transition in, you can do “blends” where you grab the little square box at the top at the start and end of a recording (e.g. if you recorded a second of hand movements, that one second recording will have blend handles at the start and end.). If you drag out the blends you will see a curve shown - it uses a bit of the old vs new position information to more smoothly move the hand etc between the two locations. (The worst bit here is when you arm the dragger behavior, you cannot see where the hands where before. So its a bit more guess work to get things to line up. However, you can overcome this as well by adding a second dragger to the puppet - when you arm the second dragger, the first dragger values are still visible. It will effectively average the values between the two dragger recordings if both are trying to move the same drag handle.)