Massa

02:14 Jan 30, 2018 

Laurence's "crowd scenes" sounds like it could work too (although it sounds to me like it might be slightly more specific in scope).

Here's a review that refers to the "handling" of both "chorus" and "crowd scenes": https://goo.gl/sRK9k6

As far as the opera in question is concerned, there's a review here of Pia de' Tolomei that talks about the chorus standing "in static clumps": https://goo.gl/JNyeB6

In alternative to 'treatment' or 'deployment', it seems "staging" is pretty common, see here: https://goo.gl/2JuzC3 and here https://goo.gl/kAG4by

This one, on the other hand, refers to "static direction of the chorus": https://goo.gl/ex4FPL

21:52 Jan 29, 2018 

..given the context, the reference could be either to battle scenes (i.e. Ghibellini vs. Guelfi, since that is the setting of the opera) but I haven't been to a production so am unable to confirm these eventual battle scenes; but 'crowd scenes' might also work here.

19:19 Jan 27, 2018 

Hi all, Dan Newton found just the correct article that I am translating. I cannot give more context than that. :D

08:36 Jan 27, 2018 

Hi, I'm no opera expert, so all of this is to be taken with a suitable pinch of salt, pending the arrival of the subject matter cavalry! Mary is of course right to call for context and so, since it is publicly available, I hope you won't mind me posting this - https://goo.gl/Md5e2a - which I'm presuming is the text you're translating (it also contains the "telefoni bianchi" reference from your other question).
Tentatively, I would suggest translating "gestione fissa" as "static use", "treatment" or "deployment" and the "masse" as the "chorus" (see here https://goo.gl/tkjiFt).
Here are one or two other references to back that up:
static use: https://goo.gl/jZUbK4 / https://goo.gl/MFCjjx
static treatment: https://goo.gl/SVzD1u
deployment: https://goo.gl/CQEB65

07:43 Jan 27, 2018 

context is essential