I've yet to see any period documents relating to the 'Zeppelin fliegende panzerfaust'. The 'Zeppelin rocket-propelled ramming aircraft', aka 'Zeppelin rammer', is included in German Aircraft: New and Projected Types from January 1946 - but not the 'fliegende panzerfaust'.
Regarding the 'Zeppelin rocket-propelled ramming aircraft', the British report makes it clear that it exists only as a drawing - there are no accompanying documents to provide any context in terms of development etc.
So what can we say about the 'fliegende panzerfaust'? Well, firstly, as far as I can tell there were two organisations which bore the 'Zeppelin' name in Germany during WW2. Both of them did design aircraft but doing so wasn't really the primary concern of either.
1. Luftschiffbau Zeppelin (LZ) based at Friedrichshafen. This is presumably the company referred to in the link posted in reply #7 as 'Flugzeugbau Zeppelin'. During the war, LZ seems to have carried out a lot of wind tunnel work under contract - primarily for Dornier and Daimler-Benz, testing wings, engine nacelles, radiators etc. It also seems to have done a lot of work on rocket aerodynamics, including the A4 (V2), Drache and Wasserfall. On the airframe side, it seems to have carried out contract work on large aircraft, particularly the Messerschmitt Me 323, Junkers Ju 290 and Dornier Do 24.
2. Forschungsanstalt Graf Zeppelin (FGZ) based at Stuttgart. This organisation did a lot of work on parachutes - including bombs dropped using parachutes, brake parachutes, the aerodynamics of parachutes etc. - experiments with firing into water, acoustics, medicine and physiology, wing containers (such as that weird experiment with personnel pods on the wings of a Ju 87), the V1 launch ramp, pulsejets and experimental anti-bomber weapons. It also designed a small V-tail pulsejet fighter (having solved the vibration problem) which would have used components from the Bf 109 and He 162.
German Aircraft: New and Projected Types lists only two projects under the heading 'Zeppelin', the rammer and the gigantic Z SO 523. The latter must have been designed by LZ but the rammer? It could have been LZ or FGZ. Similarly, the V-tail 'fliegende panzerfaust' doesn't really seem like an LZ project - although I couldn't entirely rule it out.
So we don't really know which organisation designed the 'fliegende panzerfaust', assuming it's 'real'. What about the description given: "a rocket powered parasite interceptor designed by Germany in 1945 as part of the emergency fighter program with a single mockup built". I would suggest that this is entirely wrong. There was no emergency fighter programme except for Volksjaeger - and a rocket-powered rammer would certainly not have been suggested for that requirement. The 1-TL-Jaeger programme, similarly, was intended to eventually produce a replacement for the Me 262, or He 162, or both. It was longer-term and demanded a high-performance cannon-armed fighter powered by an HeS 011 turbojet. Again, no room for a rocket-propelled rammer.
I suppose the 'fliegende panzerfaust' would sit best with the aircraft tendered for the Objektschutzjaeger requirement. Some designs in this field were intended to be towed aloft - such as the Messerschmitt P 1104, Blohm & Voss P 186 (BV 40) and DFS Eber. Was a single mockup actually built? There is really no evidence for that whatsoever. The object pictured is, as I'm sure you're aware, simply a modern mockup based on the modern drawings.
Unfortunately, we know practically nothing about the design labelled 'Zeppelin fliegende panzerfaust', and nothing that has been written about it seems likely to be accurate.
