I agree. There is nothing easy about making your own space program. And South Korea is one of the most advanced economies in the world. It might not be the largest but they have similar technological level to Germany. I would actually say their technological level at this time is way ahead of Germany. Germany cannot manufacture a lot of high-tech products which the South Koreans have no issue in building. If anything I think Germany's technology base regressed since the end of the Cold War. Germany cannot build a nuclear reactor to save their life if they wanted to and South Korea builds them. And most high tech products made by German industry are even more dependent on collaboration with other nations than South Korea's. The semiconductor industry, there is just no comparison possible.
You are correct that fuel handling and storage are also big issues with hypergolics. It is quite finicky. And the hypergolic fuel that North Korea recently managed to produce for their latest ICBMs, UDMH, only a handful of countries have historically produced it.