Several years ago I read that Belgium or Netherlands or maybe Austria allowed the Jetprop to go on their register.
Surely that would now be grandfathered throughout the EU?
The Malibu to Jetprop conversion is AFAIK an STC so it is still a PA46 Malibu - no?
I believe the PH-LUX is a jetprop?
This would confirm your story.
A lot of Jetprops on D-reg, one I'm familiar with just moved from N-reg to D-reg.
I had a chat with the Jetprop LLC people at Aero last year and they have an EASA STC.
There's one registered in Sweden as well. Looks like a nice bird and performs quite well according to the owner.