UPDATE — 7 September. Homunculi are back to the way they worked on the Avalon of 2010.
The level limit has always said 200, but the experience table stopped at 99, so every homunculus got stuck there. The original 2010 table with 200 levels is back: Lif, Amistr, Filir and Vanilmirth grow to level 200 again, with their usual stats per level.
As in 2010, monsters aggro the homunculus and not only its master, so an Amistr tanks for you and a Filir pulls attention while you brew or attack.
Nothing on your side — the change is server-side and already live. Alchemists and Creators get an Embryo through the usual Bioethics quest and call their homunculus as before; intimacy still grows three times faster than official.