I've read some requests by well known modellers on FB, asking for detailed views and cross section drawings of G91. So maybe yes, they currently have only an external 3d rendition of the aircraft and the project is only in a preliminary concept phase.
I've guessed it right when Kinetic posted the riddle: I thought that it would be nice with the incoming restoration to flight condition of a real G91R, project led by Italian Air Force to celebrate her 100th birthday. And I hoped that some of the original blueprints had emerged from FIAT Aviazione drawers and arrived to kinetic model desk to help in designing process too. I lived near Treviso airbase, home of ItAF 2nd wing who operated a swarm of G91s. She's one of the first aircraft I've ever seen... But, You know, You may say I'm a dreamer, and I'm not the only one, I hope some day you'll join us, and the woooorld will live as one......