If it is normal text then yeah standard text hacking methods should be in play. Usual start for English or many European languages is to run a relative search
https://www.romhacking.net/utilities/513/
If it is something more dynamic (don't know if it would be for this but I have been surprised before, and this sort of game in this sort of timeframe is a better candidate than most) then you will probably want to investigate the code. You may still need to investigate the code if you want to change what triggers with what degree of friendship or other such factors.