Have you search uganswer (https://solutions.industrysoftware.automation.siemens.com/)?
Have you tried recording a journal (in your language of choice) where you edit a custom symbol's size?
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled
For those who are interested:
I opened an IR at GTAC and the reply was that ist is not possible to retrieve the size/width of an customsymbol yet. However the MAsterSymbol's path can be obtained by the following example code
Dim theSession As Session = Session.GetSession()
Dim wp As Part = theSession.Parts.Work
Dim it As IEnumerator = wp.Annotations.CustomSymbols.GetEnumerator()
Dim csb As DraftingCustomSymbolBuilder = wp.Annotations.CustomSymbols.CreateDraftingCustomSymbolBuilder(it.Current)