I understand, e.g. from this answer, that the phrase "not yet" is used to talk about an event that has not happened so far, but that we clearly expect to happen somewhere in the future.
I want to know if "not yet" always bears this meaning and what consequences there are for understanding if we use it in other contexts. This question is motivated by an answer on German Stackexchange that got many upvotes and states that the German "noch nicht" can always be translated as "not yet". Since "noch nicht" can have other meanings than the one described above for "not yet", I doubt this and want to check it here. For that, I picked up two cases where English learners with German background might be tempted to say "not yet", because they would use noch nicht in German.
Stating that an event, that will or will not happen in the future, has not happened so far.
Following the answer quoted at the beginning, I think one would use "still not" in this case. E.g.
1) I still haven't found what I'm looking for.
2) Despite researchng for many decades, scientists are still not capable of predicting earthquakes.
What would happen if I used "not yet" in these sentences, i.e.
1') I have not yet found what I'm looking for.
2') Despite researching for many decades, scientists are not yet capable of predicting earthquakes.
Would a native English reader still make some sense out of these sentences? Would this be the original sense, i.e. would he think "oh, that's not the best English I've ever seen, but I know what you mean", or would the alteration in meaning stay unnoticed?
Stating that some fact is not sufficient to imply some other fact
3) It was a fantastic match last night. But this victory was not yet the championship. Meaning: although it was important to win this match, we can by no means think that we already won the championship by this, too.
4) Futuristic skyscrapers are not yet Europe. Meaning: seeing a fancy skyline, like in Russia's capital Moscow, is by no means a guarantee that this country will adhere with European values or will have good and close relations with the EU. This is the phrase that the quoted German question is all about.
These two sentences are phrased using "noch nicht" in their German translations, but I have considerable doubts that it is possible to simply take the dictionary route and translate them with "not yet" the way I did. Am I right, and if yes: how wrong do these sentences sound?