What people seem to be missing with Sondland is that the reason he claims he had to presume there was an improper quid pro quo was because he didn't see Trump's July 25th readout with Zelensky where he made that clear. His claim was during his work toward getting a meeting set up and the aid released, he came to presume there was a quid pro quo.
This has been shown to be a correct presumption based on the 25th of July phone call readout, as well as Trump's and Mulvaney's public statement since this all became public.