I have Searched all over the Web,DLS and 3rd party sites for a alstom regio citadis like that used by ranstadrail and Kassel , i know one Exists as had it on a old PC that died.
All i can find is an private reskin of it. Maybe you can ask on http://trainzonline.nl, the place where the person who made the private reskin is registered. Maybe they can help you there.