In the end, I think that Reginald Foster’s rendition is the best: breviloquium, i for tweet; breviloquens for tweeting (or a person tweeting); breviloquus, -a, -um for the adjective form; breviloquor, -loqui, -locutus for the verb. This is less artificial as Cicero used this word and as well best describes what a “tweet” really is: short speech (or talk). On a note which might be less relevant to most of the world, titiatio is too close to the Filipino word for penis which the usually modest Filipino (who also do Latin) would rather avoid saying.