Yeah... The assumption that you don't know how to vent sex properly is very helpful and unrelated to your question *eyerolls*
If they survived the vent sex then you aren't a total bafoon.
So I will answer your question, yes that could definitely have stalled progress, but at that young age, they usually aren't traumatized for life.
I would start by finding out their favorite treats. Mealie worms, and watermelon are my babies favorites.
Try hand feeding.
If they run away toss the treats and slowly decrease how far away you toss them.
Eventually they should start eating out of your hand.
Then start pairing treats with touch.
With my ducks I worked with them until they let me pick them up, and I would give them treats only when I held them.
If you are gentle and slow, they should warm up!
However ducks in my experience aren't the most appreciative about being held, so they will be wiggly and unhappy. But I think it's important to teach them in case they ever need handling from being ill.
Remember though, if you want to teach them to be held, only put them down when they stop struggling. If you put them down when they fight, they just learn to fight harder the next time around.