In modern software development the debug modes themselves are often stripped out of final releases of games -- it typically does not cause any issues and it is usually considered good developer form to do so. Quite often though the text part, especially if it is external, gets left behind (a few extra kilobytes on a several gig disc is seldom worth the effort).
Even if it is there you can be in for a serious struggle to find it -- it can be in any number of places and activated in any number of ways. Typically it is something you can do quickly and beyond that I would look at other games in the franchise, other games the dev made and possibly other things in the same engine. Also despite what I said above it can also be worth checking other regions and betas if there are any.
If you can get on in the assembly world then you have a few more options. Hopefully the text you have gets loaded into memory at some point, you can then find things that would reference it in memory. You can also try eliminating parts of the binary and then anything that looks like it handles level selection is a good thing to look at. By the way if you can find the level selection function used in normal game then you might also get lucky and find it is used by the debug menu.
With the above it could also be that the debug mode was left in but all means to get to it, at least without a gameshark type device or an actual debugger, were removed. This is a bit nicer to deal with and one of the things that cheats tend to deal with, the other big one usually being so the game does not crash.
If you are wanting it to help speed up testing of your translation then I would consider instead getting a bunch of saves or a bunch of more conventional cheats to allow people to speed through it.