In my experience import and export of portals generally works best between installations with the same DNN version.
I don't think I would trust a portal import that semi-failed.
We have had that once before and it lead to lots of issues later in the process.
We managed to fix them in the end, but there was a lot of SQL involved.
I there a reason you are not upgrading the DNN 7 install to 9?
Are there any errors in theConsole (F12)