I am saying the transmission is inherently flawed if it revs at 2k rpm when on a downward slope. As to whether the engineers know what they are doing is anyone's guess. I've seen this behavior in other CVTs, so I assume that it is an engineering obstacle inherent to the CVT design that has yet to be overcome.
My 2011 Avalon will keep the same engine speed if I'm on the highway doing 75mph and let go of the gas pedal to coast for a bit when going downhill.
It would cause extra wear and tear if it disengages the gear every time to took your foot off the gas pedal for the slightest amount and reapplied.
The MPG gauge shows 99.9mpg when coasting in gear.
OP, you need to get a scan gauge and re-evaluate your driving style because it's FLAWED.