I suggest to add values and names of duplicated keys in error messages ##2601, 2627 and 3604.
E.g.: Msg 2601, Level 14, State 1, Procedure UserSettingsStorageFiltered__TR__OnInsert, Line 11
Cannot insert duplicate key row in object 'FtmAppInterop.UserSettingsStorage' with unique index 'UserSettingsStorage__IXU__UserFilter'. Duplicated values: [Path]='Key 1 value', [UserKey]=0x0000000001b5.