Confirmed and fixed. Those centre-screen messages were a flat 1.2-1.4 seconds with a hard cut, regardless of length - so 'Not enough MP' and 'Type your Super Megaphone message in chat, then press Enter' (56 characters) got the same time. They now hold for reading time - a floor for the short ones plus roughly 14 characters a second - and fade out instead of blinking away.

(On the dev branch - it will be in the next published build, not v32.)