Pure speculation here, but perhaps the spydie holes on the Para3/Para2 are not as sharp because they need less engagement to open the blades on those knives, unlike the Delica. They are generally smoother and more "flickable" than the Delica. Therefore it is possible your Para3/Para2's are not defective.
As for general fit and finish on the Delica: at one point or another I have owned three of them, including one in ZDP-189. I may be less discriminating and consider the Delica to be a high value, lower cost, utilitarian folder so I am not bothered by the faint grind lines on my Delicas (which are also present on both of my Golden-made Para3's). Other than the faint grind lines I have never noticed any issues with the finishing. Your tastes may vary.
As to the more sluggish opening mechanism on the Delica: I actually prefer the added friction in the pivot, as compared to the Para3. I think it makes the Delica feel more solid in use, which matters to me in such a light and slim knife.
Notwithstanding your misgivings, you've got a great knife in your hands. Use it and you will enjoy it more than you think.