Sounds like they are healthy, just scared to death. Usually babies are pulled at 2-3 weeks, or at least handled a bit starting at 2-3 weeks so they aren't scared of people.
It's normal for them not to be begging, because they don't think of you as someone who feeds them yet. To them, you might a predator.
I would just try to go slow, spend time just sitting near them and talking to them, move slowly and handle them very carefully. You need to build some trust.
You might have better luck feeding them from a bent spoon, it's messier than a syringe, but feels more like being fed from a parent's beak. You might also try adding a bit of applesauce or babyfood carrots or sweet potatoes to the formula to make it taste extra good for them. You can also offer them soft foods to try on their own - they are old enough to nibble on food a bit, but probably not old enough to fully feed themselves.
Also weigh them as soon as you can - before feeding. Weigh them at least once a day, before feeding, to keep track of any weight loss. If they lose more than 10% or don't start to adapt and gain weight after a few days, then you should see a vet. A vet can always force feed them with a crop needle, but it's best if you can avoid this, as it does nothing to help gain their trust or teach them to eat on their own.