Only reason to involve the SDK is writing homebrew or if you somehow have source code to the game. As you are technically doing neither then no need for it.
When you say font do you mean the characters are in terms of the pixels they take up too large for the box? That would be a font hack.
Or do you mean when you translate the text the number of characters is too many to fit in the box (common enough in Japanese to English)? In that case this is likely a pointer hack (games don't know when new lines start and end so they tend to have lists of lengths of text strings or lists of locations of text strings) and generally expected for hacking a game.