Make sure that you calibrate the Interlink via the Windows Control Panel FIRST.

Then go back in and recalibrate it in Realflight.

Then fly the plane with no wind to check it.

Note the Avistar DOES climb at higher throttles because it is a trainer. This is standard behaviour for a trainer.

As far as Trims, the Interlink makes a noise each time you move the trims.

There is one particular noise for trim center and another for trim extremes.

Retrim and listen for the "center" tone.

Since the sim remembers the DIGITAL trim settings for each plane, if you put the plane out of trim, it will subsequently return to the same state the next time you load it.... just like a real digital trim TX.