Touch if you like, but prepare to pull back your hand if you hear growling!
I have never had a rabbit reject her litter if I touch them, but I don't interfere too much. If they are not thriving, then they die. Simple as that. I don't want to raise a weak rabbit. They are poor contributors to the herd.
When a litter is born, I take out a treat for mom and distract her while I put my hand in the nest. Warm babies means full babies. Cold babies means dead babies. After a few days when mom is used to me sticking my hand in, I take the whole box out and have a look. Sometimes there will be a dead one pushed into the corner and I remove it. I have a look to make sure they are all in one piece and put them back.
They only nurse once or twice a day. The milk in their tummies makes them warm and the fur insulates then.
Have fun! They are so cute when they open their eyes and start to peep out of the box.