I have spent some time examining the reports of this pantomime and it seems to hinge around the "lawyer" who wished to see American adoption laws amended....Adoption legislation is extremely lucrative for lawyers both in Russia and the US.....the ban placed on the adoption of Russian children by US couples is an impediment to the legal sharks.

It seems the approaches to the Trump campaign were simply a means of getting access to advance the lawyers wish to have the restrictions on Russian diplomatic personnel and property reversed, so that the ban on Russian/American adoption could be lifted.
It also appears that the whole enterprise could have been constructed with the added ingredients of a "sting" should the Trump campaign people walk away.....Which they did.

Conclusions.......Lawyer ...unbalanced, or working for anti Putin interests.   Putin uninvolved...... Trump jnr.....naïve.
   American politics..... corrupt.   American News media...unspeakable.