> the problem with heat pump is require quite well isolated building to make it efficient. Also after talking with a friend he had to change all radiators in his parents home since it didn't work well with previous old one he had.

no, it doesn't require good isolation. Good isolation is beneficial, like for type of heating.

Radiators don't have an effect on isolation. However, modern radiators usually have a way higher surface area, which allows heating rooms with lower water temperature.

Heat pumps are more efficient if the difference between source and target temperature is closer.