Of,course otl it seems that the exchange didn’t happen as Leopold ended up as duke, so?
Yeah, the territorial concessions never materialized. I only bring it up here as a potential concern because OTL the sequence of events was
1617 Onate Treaty
1619 John Charles dies
1626 Leopold is made Archduke of the Tyrol
1626 Maria Anna is betrothed to Ferdinand
1628 marriage contract signed
1629 Maria Anna and Ferdinand married.
but here the marriage to John Charles would be proceeding from a betrothal presumably made sometime between 1617-19 with a marriage probably in the early 1620s. So the issue will probably be 'fresh' and Leopold will not yet have been given the Tyrol. So it could be a concern rather than a settled issue as I think it probably was when Maria Anna and Ferdinand married OTL.
And for what it's worth Ferdinand II proposed the idea of an Austrian Kingdom to his brothers in 1623. Charles left for Spain in 1624 to become Viceroy of Portugal but died on his way there. Leopold resigned his Bishoprics in 1625 in favor of Leopold Wilhelm and married Claudia de' Medici in 1626. It wasn't conceded full authority as independent ruler of the Tyrol until 1630. So depending on how Ferdinand juggles all of these players with a different heir, and three rather than two sons things could play out differently. I almost wonder if Ferdinand having more sons would make him less inclined to divide up his territories. I kind of think that after the Brother's Quarrel between the various sons of Maximilian II that he'd be leery of repeating the mistake Ferdinand I made in his will by dividing up the Austrian territories and weakening the the strength of the main line, especially at a time of war and rebellion within the Empire when their authority is being challenged.