« on: August 21, 2020, 12:41:20 pm »
This is a game I have a little interest in, and under different circumstances I'd probably have approached you about handling the hacking for you, but as things stand I'm committed to more projects than I'm really comfortable with already and need to finish some before I can think about taking on any more. But I'll try to at least give you what help I can.
First, I'm not quite sure what you think "dual-byte encoding" is, but I can tell you that the reason you're seeing all the text twice is that the PCECD has a BIOS feature which allows developers to store a redundant copy of the game data on the disc. If the machine tries to load data off the CD but detects that it's damaged beyond repair, it can then use the backup copy instead. Most games I've ever looked at use this feature; sometimes the backup copy will be a separate track on the disc (usually the last one, so that it's physically separated from the theoretical damage to the main data), but other times it's all part of the same track.
As far as hacking goes, under any normal circumstance, only the "main" copy will ever get used. I doubt any emulators actually emulate the CD controller accurately enough to allow the backup data to be seen, even if the disc image file was somehow corrupted. Even if someone burns a physical disc with the game and somehow damages it, they can presumably just make another one, so if you're making a hack, you might as well just get rid of the redundant data and save yourself having to deal with it. However, this requires modifications to the code to disable this BIOS feature, and while it's generally not difficult, it sounds like it might be above your skill level.
Now, as to the main problem of your text changes not showing up: I can't tell you for sure without looking at the game, but what format is your disc image in? If it's a CUE file with one BIN file per track, then IIRC the BIN files include all the CD error correction data. Normally, this is used to fix errors caused by the CD drive failing to read the disc correctly (due to disc damage or whatever). However, this also means that if you modify the disc data but don't update the error correction data, the changes you made will be interpreted as disc corruption. Real hardware and accurate emulators will they try to "correct" these "errors", and if you didn't change too much stuff, they may successfully manage to restore the original disc data, meaning your changes will be reverted. I know that Mednafen, at least, will do this if possible; no idea about RetroArch, but it may be the same deal.
For hacking purposes, what you want to do is convert the data tracks to ISO format, discarding the error correction data. You can regenerate a proper disc image at the end of development when you're actually releasing your work. (Unfortunately, that's another one of those things that requires you to know what you're doing, but given you're just starting out here, I wouldn't worry about it yet.) I don't know if there are any "easy" tools for doing this, though... I use bchunk, but if you're not used to command-line programs, you might have a hard time with that.
Of course, the problem could also be something completely different. PCECD games can get pretty bizarre. I'd have to spend some time looking at the game to know for sure, though.
To be honest, as you might have gathered from this long explanation, the PCECD really isn't a great console to be trying to hack for if you aren't going in with a lot of technical knowledge, and I get the impression you're relatively new to this. Putting together a quality hack for a machine like this one involves jumping through a lot of hoops even if you know what you're doing, and you're really going to have to learn a lot of stuff if you want to pull this off. Again, I wish I could offer you some direct help here, but I just have way too much going on already. Sorry :/