Speaking to the Hansa Members first:
I totally understand why making them true wonders is a good idea. It makes them somewhat unique, and gets away from the cookie-cutter wonder that National Wonders in such large numbers become... that being said, I have inferred that Headserf's philosophy is that Wonders be restricted to true wonders, actual physical structures emblematic of great works. In that vain, he removed such Wonders as the Magna Carta. He'll correct me if I'm wrong in my supposition. I'm not certain if I'm of the same opinion on this... I wish the Projects were more flexible as to their effects as I think they're use for Hansa Memberships and such would be more effective and realistic than either National Wonders of Wonders in representing the idea of league membership.
Possibily the Hansa Memberships could be a mix of National and true Wonders. As I mentioned before, they should be spread across more techs, and have differing effects and resource requirements. The resource requirements could differ according to the area of trade each Hansa Memberships are said to represent... for instance there could be Banking Hansa, Textile Hansa, various commodity Hansa (salt, beeswax, amber, furs, gold/silver, grains, etc.- all goods, trade in which, the various Hansa members indulged in). Banking Hansa would require gold/silver resource and Banking Tech and act like Wall Street Wonder. Flemish Textiles would require sheep, and generate cloth (similar to the way Broadway generates Hits). These could be a mix of National and True Wonders depending on the monopoly status of the particular business... Flemish Textiles were a longstanding monopoly, so they could be a true wonder. There were a lot of Guildhalls and generic Hansa members as well, and they could better be represented by a National Wonder that comes with Guilds tech... they could vary in resource requirements to show the diverse trades of the various Hansa.
We could also get away from calling them Hansa Member wonders, and rather have certain wonders produce the Hansa Member resource. For instance, we could create wonders such as Medici Bank and/or Jakob Fuggers Merchant Bank, and have each produce a Hansa Member resource. Similarly, Hansas represented by National Wonders could be called Baltic Salt Trade, or Scandanavian Fur Trading Cartel, etc. and produce the Hansa Membership resource in addition to whatever subsiduary effects you wish to use for that particular Hansa wonder.
All the above has the effect of removing the Hansa Memberships idea from being a cookie cutter one, and makes them unique and more distinct, even in the case of National Wonders.
As for the Oxford and Medici Bank National Wonders, I am all for inclusion of the former... it makes sense, although keeping Oxford as a true Wonder and adding an additional "Royal University" National Wonder with differing effects would also work.
I'd make Medici Bank a true wonder, with the addition of a second one, Jacob Fugger's Bank. You could have it act like Wall Street with added effects... Each could, for instance, produce Hansa Membership resources, and in the case of the Medici Bank, some resource that enhances building of Silk Road components, too. Another thought is that the Medici Bank could produce another resource, "Florins", which would be a tradeable resource similar to Broadway hits. Likewise, Jacob Fugger could produce "Guilders". These would require gold or silver to be produced. Fugger might give a free bank in each city, as a possible benefit.
All I've said above could be equally applied to the other spaceship victory components. The same ideas of making the components, or prerequisite wonders unique and differentiated in effects could be incorporated in these as well.
Finally, as I've previously mentioned, the Hansa Diet and Syndic should be moved to representation. I think some of the Hansa Wonders should be in other techs like preservation (salt trade), Banking, Pilotage (north sea trade), Representation (free cities could chose to be Hansa Members). These could be required prerequisites in addition to Guilds.
As well, all Hansa Members should require a Guildhall as a building prereq. Or a Bank in the case of a Bank Hansa.
School of Navigation (aka Henry the Navigator's School) could be a National Wonder. I've previously mentioned Cinque Ports (or Royal Navy) as a possible national wonder (a naval "westpoint", requiring 5 dockyards). I suppose "Royal Army" could be a Westpoint type national wonder - or "New Model Army"? although that comes 100 years too late. Anyhow, such a wonder should come with Professional Warfare.
No ideas for ironworks.
That's my 2 cents, anyhow. I could flush out the ideas more if they're acceptable.