The plugin actually has 3 filters:
Lens Transform is the main thing.
Lens Test is much simpler, made to inspect lens profiles whether they work as expected.
It can do just simple forward/reverse distortion without any rotation etc. This is style of transform useful for camera tracking and cg composition (but I am not doing this).
Repair is simple border filling, same purpose as Deshaker` extrapolate pixels.
Repair uses alpha channel to determine what to fill and Lens Transform in turn uses alpha channel to signal good/bad pixels.
About lens profiles
The most accessible way to get one AFAIK is to use Adobe Lens Profile Creator free utility.
To calibrate, just open checkerboard image on flat display, take about 9 shots at different angles, then put them in the profile creator and it will automatically determine distortion, fov, and lens center.
At the moment I only read "fisheye" model (there is also "rectilinear" model which I have ignored).
I made profile this way using ordinary 23" monitor. I also made water profiles, for this purpose monitor is not an option
