I've already checked and there is none, so people just use what they like. Apparently that's the rules. I've been pondering this in COVID-19 lockdown, since I saw the large display recently shown by @Tony Press here. My thoughts were: A dazzle of lanterns or A brilliance of lamps. I'm sure someone will have something else.
Unlit A shed/garage/house/barn/warehouse - ‘full’ (pick whichever’s appropriate for the size of the collection). Lit A blaze - of just the lanterns, unless something went dreadfully wrong.
If the lantern's have a military perigee is it not a "squad of lanterns"? Here is one I lit earlier this year:
In my case: "A fool's folly of pure lantern enjoyment!" (You can substitute "lamp" for "lantern" here)
Ha Ha Ha ! It’s Hoard u daft Bu**er You’re so right Wim ha ha ha oh dear I do loves this ‘ere forum ps actually I prefer hord