I know Sync is brand new, but I think the Custom Apps API should add the following properties:

Table model

• 
  isSynced : boolean, similar to a field’s isComputed property


• 
  sourceTableId : similar to a MultipleRecordLinks field’s linkedTableId property
  
  
  
  • Additionally: sourceViewId for the source view
  
  
  • Additionally: sourceBaseId for the source base
  
  
  
  

Record model

• 
  sourceRecordId: similar to a MultipleRecordLinks field’s linkedTableId property, but reporting the record not the table

Hopefully these won’t be too difficult to implement because boy would they be life savers!