Yeah, caster isn't adjustable on these cars. I don't even know of any coils that have a caster adjustment on them.
TL/DR - If the alignment is off after installing a part it might be the part that is off or their machine. If they left your car pulling to the left
twice, I'd go somewhere else.
On to the Too Long part.......
The only way the caster can be off is:
if it came from the factory like that or the subframe got shifted.
You have a bent LCA
The top hats/mounts on the coils are uneven. <- this is my bet. This is also not the first time I've read of someone have this issue with the N+ coils.
Hopefully they at least tried loosening and shifting the top mounts before bolting everything down.
I would take the car somewhere else if this place has left it pulling to the left and you've had it aligned there more than once. In all honesty take it to a Honda dealer. Some of them are easy to work with and some are not. If you go in and tell them the issues you are having and that you would like to pay to have an alignment done they are usually helpful. When people try to get stuff done under warranty is when they run into issues. I've never had trouble at a dealership service center, I might be lucky, but I've always said "hey I need this fixed can you guys do it?" My car has some significant mods on it and they mention it but never gave me crap about it.
Be upfront with them that you want to pay for an alignment, that you have aftermarket parts, that there is something wrong, & you and this other place have not been able to figure out. Call ahead and talk to the service advisor. I've found them helpful if you are upfront about everything. Especially mention that you would like to bring it in for their opinion on the LCAs and the subframe shifting possibly. At least then you will know if all your frame parts are straight and the coils are the issue. They will probably charge you a diagnostic fee, the alignment fee, and maybe an hour of labor at the worst. Its possible they would just do that alignment, charge you for that, and let the rest go.
I suspect its the top mounts on the coils being off since everything was in spec before those went on.
You could always pick up the Blox Rigid Collar Kit. It is a set of inserts for the subframe to ensure that everything is aligned as perfectly as possible. When the cars are assembled at the factory by robots they use wobble bolts so things go together quickly. It gets close but not perfect. Good enough for the mass produced car and why there is a range of setting considered acceptable. I don't know if the blox kit will fit your car as it was made for the 2006-2011 civics but it may be worth a shot.
If you get the blox kit and don't use it I would pick it up from you. I had been thinking about getting it anyway.
There is also a spoon collar kit as well.
Spoon:
http://www.icbmotorsport.com/spspricokit.html
Blox:
http://www.jhpusa.com/store/pc/viewPrd.asp?idproduct=10050