we created models of the same site on different dates, but after loading into the ContextCapture Editor, these two models have a difference in the Z coordinate.What is the reason for this?Is it possible in the ContextCapture Editor to combine these two models for calculating the difference in volume?
nevertheless, for mesh models from other projects, these properties were active and I could change the Z coordinate and scale.
What Geogrfic Coordinate System I need to choose for Ukraine?
You can attach it as reference and then change elevation for reference.
If attaching as reality mesh then it should create and set DGN coordinate system from mesh. You are correct, I do not see any coordinate system defined for Ukraine in Microstation.
The list of existing systems is here - https://epsg.io/?q=Ukraine%20kind:PROJCRSContextcapture lists only these: