Can receive messages (often), can't send/call (sometimes)
The log is here: link to Pastebin
Since I tried to call four times (and erased two of the calls from the discussion) I guess it's all about the 'renderer not found'.
I'm a bit concerned about the consistency of Jami. Just being online is not enough for me to contact a peer, to the point even sending a text message is no guarantee they'll receive it. One improvement recently, though, is that for some reason I receive the majority of their messages (I think). I did manage to call and even go video with my peers, but sometimes, it just won't work. Maybe I'm just overthinking it.
[EDIT] I asked that peer to call me. She answered
Apparemment le téléphone
☎ne fonctionne pas ;) [It seems the phone does not work.]
[EDIT 2] Problem solved: It seems that whenever more than 1 (one) Jami client are running at the same time, none of them will react to anything. As soon as I killed the Ubuntu client to let only the Android client up, my messages were all received in a couple of seconds and we even got to phone each other easy-peasy.