That's not the point, it's simply the precedent for the trade that happens in 1814
At the Congress of Vienna every agreement made from 1792 onwards was not very relevant,
And this is all based on what, exactly? There was no need to compensate Austria other than the fact that Austria was compensated for the loss of the Austrian Netherlands as proven by the excerpts. So I'm very confused why you're persisting that "there was no need to compensate" or "they weren't compensated".
Campo Formio was a peace deal which the Austrians had to accept after being crushed by the French, annexing Venice was only a way to save the face but objectively it lost a lot of territory just to annex a puppet.
At the Congress of Vienna Austria didn't want to get the Austrian Netherlands back, otherwise it would've been in their hands; the "compensation" was only a way to make it sound better than "we are annexing a territory on which we had designs for territories", Venice would've been Austrian regardless.
Whether or not Austria did or didn't want the Austrian Netherlands is irrelevant. The fact of the matter here is that they gave it up and because of the loss of souls and territory, they were compensated elsewhere, ie, Venice. Venice being aligned or a puppet or any other form geopolitical vassalage is beside the point. This is just an example of the pieces perfectly aligned.
Venice being a puppet is very much on the point, they are only gaining back what was already theirs not being compensated for not wanting to retain the Austrian Netherlands.
You're comparing apples or oranges. Territorial legitimacy is far more pressing to the interest of European courts than slavery was.
Britain didn't really do anything to prevent the Austrians from getting Venice-Lombardy, sympathies in Parliament didn't change much.