Usually the solution is simpler than we could think of! I have solved many problems like this one in my games using empty gameobjects as reference points, and I actually think that it may be even better performance wise since some of those behaves (parent and child correlations) are already being computed by the engine anyway.
Im glad you got this problem solved, your game is looking pretty good so far, I am looking forward to play it, congrats.
I’ve actually refactored mine to use 2d physics rather than transform.position, it seems to work a lot more predictably and doesn’t rely on timing. No more gap issues.
Hey, would you mind testing a thing for me? Try writing the distance inside the instantiate method instead of caching it before, use transform.position.x instead of distance to see if it works, just for the sake of science 
I was going to suggest something similar as covered something much the same using an arrow (gameobject basically) as a reference to instantiate. Nice call @Joao_Dalvi
Thanks!
Using empty objects as references is very usefull indeed
Thank you!