On a PS1 game, that usually isn't very simple. The text can be compressed, can be encrypted, can use a very unique table for that specific screen, can use a graphic, etc.
If a relative search doesn't help you, you'll have to use an emulator, like pSX or no$psx, that would let you inspect the VRAM in detail. Once you figure out what all those numbers and commands mean, you should be able to tell what routine printed the text and which one got it from disc and how.
Alternatively, you can do a relative search in a save state (or a RAM dump) to see if the the text is decompressed/unencrypted there, and then use a debugger to figure out how the text got to that RAM address.