Your paint difficulty stems from whether the faces you’re trying to paint are displaying Group/Component material attributes or Individual Face material attributes.
Paint Bucket behavior can become somewhat confusing when there is a mixture of default material faces and painted faces within the context of a group.
It’s good practice to avoid painting a group from the outside, unless you’re certain you want all the faces within its context to display just one color with no texture.
A Face has two material attributes.
A Face has a front side and a backside and each side has its own individual material attribute.
The visible parts of a model should have their faces oriented such that the front side is the visible side.
View the model in Monochrome Face Style to check face orientation. White = Front Blue = Back
You can easily flip face orientation. Right context click on a face > Reverse Faces
I notice several walls where the front of the face is painted but the face is flipped backside (blue) facing out.
Groups/Components have one material attribute.
When a group is painted from outside its context, all the default material faces within the context of the group display the group’s material attribute.
However, even though those faces display the group material, their individual material attributes are still the default material. They are merely displaying the material attribute of the group that contains them.
You can determine this by viewing their material attributes in the Entity Info box.
Conversely, a face that has been painted with a material other than the default material while working inside (within the editing context) of a group will always display its individual material attributes, regardless of the material attribute of the group that contains it.
Thus, painting a group from outside its context will not change the material displayed by those faces that were painted while working within the group’s context.
Hence, you must open the Group/Component for editing to work with those faces.
Open the Materials browser and the Entity Info dialog box. Those are the best tools for sorting things out.
Entity Info displays the material attributes of the selected entity.
You can easily edit a selected entity’s material attributes by clicking on the material thumbnail image in Entity Info.
The Materials Browser offers broader control over all materials in the model.
-Geo