It's not a modded version that can be extracted and used as is, it's actually a port.
Hmm, that's not the way it looks from the files in the Dracula X Chronicles ISO, and anecdotally from attempting to play this SOTN version via running the PSP game on a modded PS3 (in that case the base drac x game plays fine, but when you go to load the SOTN game within the PS3 crashes).
Also, upon extracting it you get a resources folder (PSP_GAME/USRDIR/res) and within that you get a 'psp' folder which has the dracula x psp remaster, a 'peke' folder which I'm not sure what it's for, a 'pce' folder which appears to have a PC engine emulator and the PCE version of dracula X, and then finally a 'ps' folder.
Within that folder you've got many files that are the same exactly as the PS1 version and then an array of .BIN files with the same names as the .BIN files containing the game data on the PS1 version. The file contents are different however, and there are some new ones, like mar.bin which presumably contains Maria data. It really looks like the PSP version kicks to PS1 emulation mode when loading the game and essentially runs a modified PS1 ver.
What I'm interested in doing is, if one could understand the .bin file format, is replacing/modifying certain files in the PS1 version to bring in Maria as a playable character and perhaps swap in the new translation. I haven't seen any documentation on the .bin files as used by Konami so that's a blocker, but I do know that people have worked on making extensive modifications to SOTN in the past. It seems to me if someone with experience modding SOTN previously took a look at this we might be able to make some progress.