The reason we are advocating for upping humidity is because its not a big deal if it spikes, it wont “drown” the ducklings like it might earlier in incubation, if kept high for many days. But as they are hatching they are no longer in danger of having too small of an air cell or too much water in the amniotic fluid since those are problems that only happen with prolonged high humidity before lockdown. These ducklings are starting to breath with their lungs, not relying on the shell for that.
With humidity at 50% i would worry you are still in the danger zone for shrinkwrapping or stuck babies. of course its still up to you, i know it must be hard to have someone else watching them.
Best of luck! Cheering for you!