Hi Ingo
I've got 919, and that includes left-over standard silhouettes. I too have seen that there are many ICAO codes for which we haven't got any sort of silhouette, never mind photo-ones. But I reckon that the missing ones have never shown up on RadarBox, sometimes because they don't have electrical systems for the equipment, and sometimes because there aren't any flying at all.
I haven't got the time or the enthusiasm to fill all the gaps, but I am happy to do new photo-silhouettes when a missing type actually turns up on RadarBox.