[TeMPOraL]

E2EE only applies to data in transit, not data at rest. Talking via E2EE chat client means only that third parties in between cannot read what you write. It doesn't imply the messages cannot be recovered from your device, or your conversation partner's device, and it definitely does not imply said partner can't just leak them, whether accidentally or on purpose.

I'm not sure how E2EE came to be interpreted as to mean "totally secure against everything".

[iudqnolq]

I think it's the colloquial meaning of "end", as in "be all end all". I'd think something like "full in-transit encryption" or even "phone to phone" would be clearer.