hehe, hihi, hoho - "specific purpose" laughs. "Hehe" is smug, "hihi" is that poorly disguised laugh, and "hoho" is Santa Klaus style.
kkkkk - the letter K is called ⟨cá⟩ [kä] in Portuguese, so this represents some really loud cackling. More to the original spirit of "lmaaaaaaaaao". (Myself use this quite often.)
hueahuea - it's H plus some random combo of U/E/A. Uncontrolled laughs. Likely the origin of the "hue hue" meme. Can be further reinforced by bashing the keyboard randomly, as "huahuaeilohauerhlçafdsaç".
"morri" (I died) - same spirit as Italian "muoio".
In Italian I've seen mostly "ahah" and "muoio" (mentioned by the text), plus "mdr" (the text mentions it for French) at least once.