Hello, and thanks for writing back.

OK, that’s many points to discuss.  First, I don’t blame you for the mistakes, everyone does mistakes especially on the first days, I am only here to make sure the map can stay a reliable source of information, because lots of people are relying on OSM to provide good data.  And indeed, some university campuses may have changed and we are always happy to have more eyeballs to spot new changes there.

About the discussion points here:

1) As I mentioned, building shapes are obtained by numerical imagery, those are special drawing layers provided by public authorities with the correct outline of every building.  A fellow mapper routinely imports new buildings, so that you don’t have to do it.  If you use the online editor it is possible to see this layer (UrbisAdm) but I would not recommend tracing on it directly in the online editor, it would take too much time.

2) Postcodes and city names are automatically obtained from existing areas.  For instance, if you type "1050, belgium" in the search box on the main osm.org website you will obtain the area where every point automatically gets this postcode.
The confusion is maybe because what you believe is "the system" is only the "iD editor", i.e. the Javascript program running behind the Edit button on the main osm.org website.  This is a a simple editor for simple tasks, and usually what people will use in their first months of editing.  This is a very basic piece of software, it is much less powerful than what the OSM ecosystem can do.  And indeed, iD cannot handle postcode zones used in most European countries and still provides countless empty text boxes.
So this is just to avoid you wasting time filling information that will not help anyone.

3) Here is an example.
https://www.openstreetmap.org/node/7206029850/history
In version #1 the address is correctly written in both languages, in version #2 by you, the French part is erased to only keep the Dutch name.
Another example is the ULB campus here: you are the editor for version #7, where deliberately erased a valid wikipedia link to "nl:Campus de la Plaine" and made it into "nl:Pleinlaancampus" despite there is no valid wikipedia page with that name.
https://www.openstreetmap.org/relation/13535797/history

4) I will agree that you had to intention to touch the VUB campus but as long as the OSM database is concerned, you touched it anyway.
https://www.openstreetmap.org/relation/13366042/history (you are version #6).  It seems that you used the scissors function to split an area into two parts, transforming the main campus part into two U-shaped lines instead of one single area.  Don’t worry, I fixed it.  I suppose it was just an accident when using the editor.

Have a nice day.