I don't think that it would be necessary to literally transfigure an AGI. Since it's possible to cast spells which react in a certain way to a trigger/specific change in surroundings, there's likely potential for creating artifices on the complexity level of scripts/programs using spells.

I think it would take quite a while to advance this science to the point where it could create an AGI (perhaps sped along depending on how easily it was integrated with Muggle computer science), but I think that if HJPEV thought about creating powerful optimization processes using magic which actually did what he intended, a huge power boost would result. Especially because AFAIK, the wizarding world has no parallel to programming, so only Muggleborns would really have a hope of understanding what he was doing.