Those are nice generalities but I think they ignore reality. Jami seems like sort of a side project to its developers. Bug reports often are answered with a suggestion to make sure everyone is running the latest version of Jami, which is often useless advice. Like if you try to call your friend with your new phone and the call doesn't complete, it's unhelpful for your phone manufacturer to say your friend should get a new phone. You might be interested in helping fix the problem but your friend just wanted to have a phone conversation and doesn't want to get dragged into a debugging project. It's even worse if the other person is not your friend but rather is someone you just met and exchanged numbers with. If you try to follow up with a phone call and there is a problem, GAME OVER. You permanently lose contact with that person. You can't possibly suggest Jami as a Skype replacement after that happens to you once or twice.

Another thing with comms programs in general is you really can't debug them with just one computer. Their whole function is to let two computers talk to each other, so you need two computers where you control both ends and ideally control the network as well, so you can insert delays, network faults, etc. If the Android version has trouble talking to the Iphone version, you need both kinds of phones. I'm not sure if Jami's devs really understand that. I've worked on telecom stuff in the past and it's just the reality of that field.

Yet another (I'm not sure of this) is that Jami is a peer to peer program so I suspect some of the problems revolve around firewall traversal gotchas of various types. I don't know if there is a cure for this while keeping the basic architectecture intact. I do like it in principle and I know that people get BitTorrent working reliably without too much trouble, so maybe Jami is just missing some trick.

Finally, Jami is pretty old and back in those days, people hadn't really thought about the subtleties of encrypted group chats. Signal does a better job, and these days there is a standard (RFC 9420) for how to do it (I don't know if Signal follows this standard). It would be good if Jami were revamped for that, but 1) that would break interoperability again, and 2) I don't know if it's workable at all with Jami's architecture (serverless, using a distributed hash table for peer discovery).

For now I've sort of given up on Jami and am trying to figure out what to use instead. It's unfortunate that the main devs don't seem to have that much interest in making Jami reliable. Randos like me capable of making small contributions can't really help much with more involvement from the experts.