The Nevatons may be fine microphones, I don't know, but this comparison is iffy. These are two very different kinds of microphones.
The Neumann AK 50 is a very high quality supercardioid with rolled off low-frequency response, more like a speech microphone than a general music microphone. Its response extends to very low frequencies and its directional pattern is well maintained down there--just with a large rolloff that's baked into the capsule design. I suspect that it was mainly intended for film and video sound, TV studios, podiums, conferencing and the like, although Neumann doesn't say so.
If I had the KM 150s that I used to own, and were using them as main microphones for music that had important low frequency energy, that would be an odd choice since there are equally good supercardioids that don't have the rolloff. But if I were doing it anyway for some reason, some serious low-frequency EQ would be in order, which would also tend to increase the sense of spaciousness. Not doing that would be incomprehensible to me, given the nature of the microphones and the program material.