No. There is nothing else you can do. You will only get the height values when you export blocks. Exporting blocks is useful if you want a DXF version of your Allegro symbol.
For exporting a board, it is best to NOT export blocks. This will get you accurate component instance refdes and placement information. You already discovered the refeds issue. When components are placed on the bottom of the board, exporting blocks will not produce the correct view. Again, this is because the block is created from the symbol definition. When you place the component on the bottom of the board, Allegro adjusts all of the layers according to the placement, (Top becomes Bottom, etc.) . DXF does not have a mechanism for doing this to a block because DXF is not aware of a PCB's layer stackup. In DXF, the block can be mirrored, but the result is equivalent to placing the component updside down on the top of the board.