Ahaha, I see the problem.
So when I defined transform ts_acBounce(), it has 4 parameters (stuff in parenthesis): dist, ts_speed, pt, rt
If the parameters already have a default value (so if they = something), you don't have to rewrite it in the script unless you want to use a different values. Only dist requires a value since it doesn't equal anything. You can set dist to a default value if you want.
When you did at ts_acBounce(dist), Ren'Py is looking for a variable named dist, but that doesn't exist of course since you didn't define it.
What you can do instead is this:
show angel at ts_acBounce(insert the number for how high you want the bounce to be)
There are examples of how to use the transforms at the bottom of the rpy file!
Hope that clears things up!