A planet was terraformed in humanity's distant past by technologically superior beings. The planet is very similar to Earth. I understand blue stars are highly radioactive and thus don't have real habitable zones so the planet's orbit is placed where it has water available in at least its main three forms.
Because the planet has to be a very large distance from the star it has an extremely long year and seasons lasting longer than a typical lifespan.
The Question - What are the main concerns that were mitigated, including radiation, by the makers? What methods could have been used to do so?
Science based answers are preferred. Handwavium and unobtaninium elements are acceptable but not magic as this is meant to be a science fiction world. It is okay to vary the planet some as long as humans can still live somewhere on the planet without high tech being necessary.