So basically, argument from authority. No Good.
This is pretty bad, but so is having had your private key compromised in the first place. It should be fixed next time they do a flag day.
Other than that, and the rekeying issue (keys are only renewed when the client is closed. They should be on a period of time, to make forward secrecy really effective), nothing else bad was found.
Notice that, for a couple years now, effort has gone into polishing (toktok) toxcore and documenting things, rather than else (eg: adding fancy features). That's a good thing.
Tox might be understaffed and progressing slowly, but there's nothing fundamentally bad about it. They got a bunch of important things (really distributed, DHT, public keys as addresses, temporal keys for forward secrecy, always end to end encrypted) right. I'm not aware of any other project that got this much right, unfortunately.
If only if Tox got more attention, it'd gain developers, donations, and the possibility of getting a proper audit done.
Tox has not had this amount of attention and it is written by people who seemed to sincerely believe that using nacl/libsodium made tox safe. If that is not a huge red flag, then I don't know what is.
Telegram is not encrypted by default and when it is it uses a weird protocol, which people warned about from the beginning. The devs were cocky even after a probably unintentional backdoor was found that would have let the server mitm every encrypted communication.
The difference between these three for secure communication is huge.