What exactly are they using to repair the large gap between framing? Does this pose an issue later on? The location is on the 2nd FL in the Master Bedroom.
Do you have any shots of the exterior? Hard to say without seeing the whole thing. Since you were there, what did you see?
here is a pic of the exterior
This is not a DIY repair site. You might hire someone to inspect and answer your questions. Besides how would anyone know what material is being used when they only have a photo to decide. Really?
Hard to tell from the pictures, but it looks like merely an air gap. That is usually sealed with expanding foam in my area.
With all of the problems you are having with your new home I would advise you to hire a local Inter-Nachi Inspector. Use Inspectorseek.com to find a qualified inspector in your area who can perform construction phase inspections on your project. You will be glad you did.