You are correct. I have a 9VE with a DIY trigger job that I copied from Jeff's excellent videos. I did not and will not replace the striker spring which as you noted is located in the slide between the sear and the fireing pin. My fish scale indicated a trigger pull of 11.5# when I started and after polishing the sear cam and all metal parts in the housing(located inside the rear of the grip below the slide), removing the pigtail spring and replacing the outside cam spring with a lighter one, my trigger pull is now smooth as glass at 6#. I have not had any problems with it since the trigger job with the exception of two stove-pipes my nephew managed last Saturday. Once we fixed his limp-wristing grip, he went through 50+ more rounds without issue.
Came back to edit a bit. I should also have mentioned in you're tag line you say trigger spring vs striker spring. There is a trigger return spring on the top of the trigger assembly. I have seen where someone has a lighter spring to replace it but I felt the benefits were out weighed by the price.