You're probably thinking about the fact that Swahili uses a slightly different alphabet than English, with some additional letters. There's no other way to write "Hakuna Matata" in Swahili than how it's already written.
If you're interested in learning more about the Swahili alphabet, here are some additional letters that are used:
* Ch: Like the "ch" in "church"
* Sh: Like the "sh" in "ship"
* Ng: Like the "ng" in "singer"
* Ny: Like the "ny" in "canyon"
* Uh: Like the "oo" in "moon"
Let me know if you have any other questions about Swahili!