Condensation Has Appeared Under The Crystal Of My Mudita Radiant. What Does This Mean?

This indicates that moisture has breached the case's seals and entered the watch, which is a serious issue that can lead to rust and corrosion of the delicate movement. 

It is crucial that you take the watch to a service center as soon as possible to have it professionally dried, inspected for damage, and its seals checked and replaced if necessary.