Jisho

Weblio, a monolingual dictionary, also does not have that word. And weblio pulls from a bunch of dictionaries.

But Jisho has 観賞 and 会 (suffix) so I don't see it as inadequate coverage. No less adequate than the monolingual dictionaries, or at least some of them.

Yeah I don't think this is in any dictionary, I checked a bunch of others not readily available on the web. At least from my experience JMdict draws a lot of inspiration from 大辞林, so completely missing entries are rare. If you think this word warrants its own entry though I'd encourage you to go add it to JMdict yourself:
http://www.edrdg.org/jmdictdb/cgi-bin/edform.py?svc=jmdict&sid=