I can see that R0J0hound is probably not really interested in these older plugins, but... perhaps there is a small chance of having a look at this:
It seems like if you have Shaders that rely on extend-box-horizontal and extend-box-vertical to work they get messed up when pasting (things that happen on the very edge do not happen), because, I'm assuming, Paster doesn't add anything to the sprite size. An option to overcome this is not having your sprite fill the entirety of the image, even a 1px transparent "outline" helps, BUT... in my case that's not an option, need to have the correct sprite size.
Tried looking into the source code, it seems like there may have been something that deals with this, but it's commented out. My skills are insufficient to figure it out... if there's any chance of R0J0hound or someone else who understands plugins to look at this I would be eternally grateful.
To make it easier I have prepared a little demo capx (with the shader included): h t t p s ://files . fm/u/7epu5z3v#_
And example images here: h t t p : //imgur . com/a/1rlYp (Will have to remove spaces, sorry).