@MichaelLiu , i think I understand your consternation in that (a) TurboTax is not making / allowing for treaty based taxation ( generally this is done by changing the asset value as an adjustment on form 1116 -- see instruction s for 1116 and (b) you may be getting more of a foreign Tax Credit than you are entitled to. -- YES ?
Recognizing that the purpose of the foreign tax credit is to reduce the eliminate / ameliorate the burden of double taxation. Thus if you paid 26% to Italy and you pay another 20% to the USA, the Foreign Tax Credit should be 26% because you will still pay the 20% to the USA plus State Tax ( where there is NO Foreign Tax Credit).
The other and harder way is to go back to Italy, show them the treaty ( most rates are bilateral ) condition tax @ 15% , and because that is what you pay to Italy, you claim the 15% as Foreign Tax Credit.
Does this make sense or am I in the left field ( sometimes I do get lost ).
pk
