Oh wow, I had no idea the Investigations 2 translation was finished. I was discussing with a friend just this week about my trepidation towards a fan translation in a series that lives and dies by its text. I'm really happy to hear how much care has been put into the translation and how faithful it is to the content and the spirit of the series.
As far as denoting laughing strangely, they did that in Ace Attorney 1 as well. In the 4th case, von Karma says "Tsk, tsk, tsk" and Phoenix comments that it's the "same evil laugh that Edgeworth has." So maybe even the odd laugh in Investigations 2 is actually a carefully planted reference as well!