Re road cranks 50/34 , first of all there's the whole technical aspect of front and road derailleurs and capacity with big cassettes (of which I too am not up on) , but most of this stuff is designed for 1x systems, well a 50t cassette anyway.
secondly, re a 50t chainring, add 20 or 30lbs to a bike and you'll see first hand that you won't be using the 50t very much, so I'd strongly suggest looking into smaller doubles, stuff like 42/28 or something, and then you'll have the added bonus of using a smaller, specifically tighter cassette with smaller jumps......but you're going to have to get good reliable info on what components work together.
good luck
Yeah, The 11-50 is almost certainly intended as being for a 1x setup. I have to wonder if the RD will wrap enough to handle all that and a double. The
18.5-123.5 gear inch range seems like a bit much. Personally I find 18.5 to be lower than I want/need, but many here want/need that, but 123.5 on a touring bike? Seems like gross overkill to me, but we each get to pick our poison.