Does placing additional capacitors in parallel with CJ7805 affect its performance?
The regulator needs a bypass capacitor to be stable. The Teensy needs one too. The farther a capacitor is, the less effective it is. If there is 1cm between regulator and Teensy, you may only need one. If they are 1 meter apart, you definitely need two. Since they are on same PCB just draw both and you can choose later to leave one out.