One thing right off that bat that is odd is:
ICE pdf: 01=UPDI
Datasheet from AT1614 shows 01=RESET !!!!
It shows default fuse is 01 - why call it Reset instead of Default Value?
Q#1 - which is 01? UPDI or RESET? I am guessing UPDI but will play with it later tonight to find out.
Q#2 - if you don't need a physical RESET pin feature, doesn't it make sense to leave it UPDI all the time? What would be the downside?
Q#3 - Is there an AVR042 type document recommending a pullup, capacitor, or reverse biased protection diode? If not, are these recommended/necessary/or will prevent programming?