Inconsistent Return Type (FamilyType vs. ModelInstance) in pull request with FilterByCategory() [BHOM Excel]

#### Description:
When using BHOM from Excel to extract Air Terminal instances from a Revit model, I notice that objects belonging to different Air Terminal families are returned as ModelInstance objects. However, within those ModelInstance objects, a FamilyType appears to be stored as InstanceProperties. The ObjectFromRevit descriptions suggests that an object can be one of three types (BHoMObject, ModelInstance, or DraftingInstance), but it seems like the FamilyType is being handled differently.

#### Expected behaviour:
From description of ObjectFromRevit, It was expected to return one of three types:
- BHoMObject for FamilyType
- ModelInstance for FamilyInstance
- DraftingInstance for ViewSpecific Instance

I suspect this initiation store a FamilyType as an InstanceProperties in the caches as the function working on a ModelInstance

Am I misunderstanding the BHOM data structure, or is this a bug in how BHOM is interpreting Revit families?