Copy data from another cube (with different dimensionality)

Yes, there are some function in the financial business rules api to support this:

api.Data.ConvertDataBuffer
api.Data.ConvertDataBufferExtendedMembers

With the first function, you define the mapping between the cubes on your own, the second one uses the extended dimension definition for the mapping.

Here is a sample for ConvertDataBufferExtendedMembers

Dim sourceDataBuffer As DataBuffer = api.Data.GetDataBufferUsingFormula("cb#CubeName:A#All")
targetDataBuffer = api.Data.ConvertDataBufferExtendedMembers("CubeName", "ScenarioName", sourceDataBuffer)
Dim expDestInfo As ExpressionDestinationInfo = api.Data.GetExpressionDestinationInfo($"C#{api.Pov.Cons.Name}")
	
api.Data.SetDataBuffer(targetDataBuffer , expDestInfo)

Here is a sample for ConvertDataBuffer

Dim dataBufferConvInfo As New DataBufferConversionInfo
	
Dim dataBufferConvDimInfo As New DataBufferConvDimInfo
Dim dataBufferMapItem As New DataBufferConvMapItem(DataBufferConvType.MapSourceMembersToFirstDestMember, "UD1#Top.Base",  "UD1#None", 1)
dataBufferConvDimInfo.MapItems.add(dataBufferMapItem)
dataBufferConvInfo.UD1Info = dataBufferConvDimInfo

dataBufferConvDimInfo = New DataBufferConvDimInfo()
dataBufferMapItem = New DataBufferConvMapItem(DataBufferConvType.MapSourceMembersToFirstDestMember, "UD2#Top.Base",  "UD2#None", 1)
dataBufferConvInfo.UD2Info = dataBufferConvDimInfo
	
Dim sourceDb As DataBuffer = api.Data.GetDataBufferUsingFormula("cb#CubeName:A#All")
Dim targetDb As databuffer = api.Data.ConvertDataBuffer("CubeName", "ScenarioName", dataBufferConvInfo, sourceDb)
	
Dim expDestInfo As ExpressionDestinationInfo = api.Data.GetExpressionDestinationInfo($"C#{api.Pov.Cons.Name}")
	
api.Data.SetDataBuffer(targetdb, expDestInfo)