Congrats on your gosling!
Assuming you have a forced (circulated) air incubator, opening it briefly to get the unhatched eggs to candle them should be ok. You can add a bit more warm water to the channels if the humidity has dropped too much after putting the eggs back in. My Chinese geese hatched in around 31 days, so the others may still be working on it.
This comprehensive
guide by Pete55 will answer your questions about internal pipping, which you can typically see by candling.
The hatched gosling will be fine if left in the incubator for 48 hours (72 hours is the maximum, and I prefer to put them in the brooder sooner so they can start eating and drinking).
Let us know what the candling shows - pics are most helpful. Best wishes for a great hatch!