your argument is besides the point.
It´s pretty simple:
Let´s say the lawyer would have been a Kremlin staff member and would have given Donald jr. intel on how the Russian government finances the Clinton campaign, would it be treason for Donald jr. to receive it?
That´s a clear no.
It would have been more treasonous not to try to protect US democracy by not getting hands on the info and publish it to the public.
The whole story is a non-starter, even if it would be substantial.
Donald jr. as a private citizien was free to meet and talk with whomever he wanted.
Even with Russian officials. The Logan act was not designed for this.
Even Trump asking publicly in the rally the Russians to hack the DNC and publish it, is a Nothingburger.
He is free to do so.
There was no exchange of any kind. Especially not money involved what is necesssary for the respective laws to be considered touched.
In 1980 (?) the Dems decided that handing over Poll data is money-like value, but also this interpretation wouldn't´t apply since hacking a server is not a service you can buy legally.
Trump can ask or wish for as much as he wants that the Kremlin does something. We all can.
It would only be tricky if there would have been a contract of exchange in someway. Let´s say US will lift sanctions. But it´s a big if since the rally was still on.
And that´s actually imho what this whole charade is all about:
The Dems want to narrow the possiblities of POTUS to set the policies and want to prevent that he reverse the sanctions on Russia.
Trump would be the most succesful President ever if he could solve those conflicts Obama created. The bargaining chip to make Russia complicit is the sanctions.
But that´s just my oppinion.
Long story short:
Even if the plot would be true, there is no legal consequence.
And you are right! Only question of interest is:
What happened and how did influence the elections?
But nobody is willing to give a straight answer to it.