You can read up on EU political institutions on Wikipedia, but it's pretty tiring stuff. It's complicated because it consists of a sequence of treaties, each extending its predecessor. International treaties are pretty turgid, and Wikipedia doesn't do a very good job of making them clear.
I don't know anywhere there is a clear, plain and unbiased presentation of the EU institutions.
As regards growing pains, I think the problems are not a matter of adjustments that need to be made; they are fundamental to the principles of the EU. The idea was to create a region where nations would not go to war with one-another, because they were bound together by trade.
For that to work, trade had to be conducted on a level playing field; that meant free movement of capital and labour, so that corporations could invest where the profits were greatest. At the same time, there had to be controls on government subsidies; governments were supposed to privatise everything, and could not use taxpayer money to help their national champions.
The UK privatised nearly everything; other countries weren't so enthusiastic.
Without these rules, the EU is nothing.
I don't see how the EU can "grow up" out of that. It's not a set of policies, that can be tweaked by a stroke of the legislative pen every few years; it's a bunch of international treaties, with 27 signatories, with many of the signatories having held national referendums on them.
Regarding "Volt Europa": I've never heard of it. Are they new? They've never canvassed me, so perhaps they came into existence since Brexit. Ah - in the 2021 local elections, Volt UK stood one council candidate, somewhere in Warwickshire. They've never stood a candidate for the UK Parliament, nor any European Parliament candidates. They've never won an election. Apparently they are federalists; even among pro-Europeans in UK, not many want to subordinate the UK to an EU super-state.