I am not from Laminar Research; just a flight simmer from down under.
I had to consult Dr Google to ascertain what a UDP was.
X-Plane 11 is a totally different package to X-Plane 10. Many planes used in XP10 will not work in XP11 unless they have been designed or modified for XP11.
In your situation you could try to download your current XP10 aircraft into the XP11 version of Planemaker and then save as a XP11 version. This may solve your problem regarding your home made aircraft.
Regarding your hardware, all hardware has to be installed through X-Plane. No other way. Not even through your PC operating system or using the software supplied with your hardware controllers. The hardware software should be totally removed ie no traces, from your system before you calibrate through X-Plane. In addition the hardware should have USB2.0 connections.
In calibrating your hardware you need to ensure you do not assign 2 or more buttons or levers to the one process or 2 or more processes to the one button or lever..
Hope this has helped in some way.