Your transition to soil rooting sounds careful and is a good method. I agree the wrinkly leaf is slightly concerning, but the new unfurling leaf is a good sign.
Variegated varieties require more light than their non -variegated counter parts. More light requires more water but I would always err on the side of caution because bouncing back from under watering is much easier than recovering from root rot for overwatering. You might consider raising the humidity instead of opting into more water in the soil and you can use a pebble tray under the pot filled with water instead of buying a humidifier. Make sure the bottom of the pot is above the water line in the pebbles.
It’s inevitable that this plant will lose it’s oldest leaves as it makes new, but also consider the possibility of pests and carefully inspect all the leaves for signs.