I like my 11-32. I can stay seated on steeper hills now, and stand up on the extremely steep grades.
The 11-32 worked on my short cage Di2 derailleur. And there's many reports of it working. The top pulley is very close to the largest cog, but it shifts fine.
I'd put one on and try it. Make sure your chain is long enough -- with the back wheel off the ground, turn the cranks by hand and with the chain on the big chainring, carefully shift to the largest (32) cog. You want to see a jog in the chain where it follows the pulleys, it can't be stretched out straight.
Then, in a quiet parking lot, use the big ring and carefully try shifting in and out of the 32 cog.
You don't normally use this crossed-chain 50-32, but it's easy to shift to it accidentally.