I think it is outlook screenshots because it is replacing Exchange not the client.
Kopano complained about them previously, Kopano do a VERY similar product ;)
As a security person when I see products implementing a large numbers of protocols in a mix of server side JS, PHP, C++ and others I get a tad nervous. There are problems Exchange has which they sidestep, but whilst audit is mentioned I didn't see one published.
Kopano has some published vulnerabilities fixed, so presumably someone looked at it, but not all the allocated CVEs are public yet if I'm reading things correctly. Still I suspect the secret is to firewall carefully on deployment, distinguishing what needs to be public, and putting the usual controls around it.
In my experience integrating Jitsi makes jitsi more complicated, and less "easy". But it starts pretty easy (click this link in compatible browser).
