You are reading it correct. Hot Reloading is only really useful when you are making subtle tweaks to algorithms and or variable values. If you modify or add a class the resulting files are not going to provide the same API and need to be reloaded into UE4. If you are interested in the details on why this is a complicated problem to solve you can check out posts like these on Stack Overflow: hot reload - How can one implement hot-swappable C++ modules? - Game Development Stack Exchange