Don't know if this has been mentioned by Dan Dillon of WOTC was asked about part of this:
Dillon: Hey
#dnd folks! Have you had burning questions that haven't been covered in Sage Advice or answered by Jeremy directly? Please ask those questions in response to this tweet! I won't necessarily be answering them directly, but I'm compiling to see what needs answers.
#WotCStaff
PickAxed Asked:
Is the area of a darkness spell opaque, i.e. blocks line of sight? So, can two creatures in a large well lit room standing on opposite sides of the area of a darkness spell see each other? I’m guessing not but just trying to reconcile the spell against how normal darkness works.
Dan Dillon responds:
Without some ability to see through darkness, whether magical or mundane, that area is impenetrable to vision (heavily obscured, in game terms).