tbf there is not really a good solution to the 'ephemeral aspect' problem
the only way to truly not sync metadata to or btwn servers at all is to use a p2p model, in which you cant send anything if one of the parties is offline
simplex might be a bit better in this regard, but still relies on servers for syncing. at least it doesnt extensively replicate metadata like matrix does though
so it depends on your threat model whether this is a compromise or not
spend more time in the shell. you will naturally learn the most commonly used commands and useful flags for them. soon you will be surprised by how much you know. having good typing speed helps reduce the friction a lot. i have not found need to specifically "memorize" anything consciously.
for obscure things, write a script and put it in a scripts folder, have a comment at the top explaining what it does for reference later.
what alternative do you propose for saving messages when the recipient is offline?