I don’t know how to mark this post as [solved], but I’ll try to make a summary of the lessons learned here anyway:

lr-fbneo-msx needs all MSX BIOS files in on pack named msx.zip in /home/pi/RetroPie/roms/msx/msx.zip lr-fbneo-msx needs ROM files to be zipped and verified against DAT checksums (the filename and CRC must match) MSX ROMs that are downloaded together with lr-fmsx does not work with lr-fbneo-msx (CRC are different for all files); you have to find the right BIOS files elsewhere. I still unable to load ROMs with lr-fmsx (however lr-bluemsx is a good alternative so far) In lr-bluemsx you can use the keyboard in MSX if you add a input_enable_hotkey in /opt/retropie/configs/all/retroarch.cfg or /opt/retropie/configs/msx/retroarch.cfg:
input_enable_hotkey = "tab"
Normally you would press "F1", when enabled you have to press "TAB + F1"

Thank you @mitu and @Folly for your help!
Happy MSXing

@zering

Ok, I didn't know that.
Too bad, this isn't a solution after-all.

Well, I keep it in mind.
Perhaps there is somehow a solution.

Btw.
Isn't there something to find on the Retroachievements webside ?

@folly No worries. You should play it. I really enjoyed that game, except for the final boss!

I solved the problem. I had a BIOS file in the Shared Roms folder with a lower case extension instead of UPPER CASE

I do confirm, all systems are there to scrape. Very cool.

@mitu Ah I see! That makes a lot of sense. I've got it now thanks! Just need to figure out what buttons I've got and it's all dandy. Although I guess I also need to map some of them so I can still exit retroarch.

@folly Thinking about it, is it possible it might work on other cores? Is it a functionality all the lr cores share?

@mitu thanks for the response. yes, i've just tried changing this - i accessed the RGUI, navigated to Options - MSX Video Mode, and changed it from NTSC to PAL. after resuming the game, the music is slower but i no longer have control of the game - i.e., i my d-pad won't move the character and my buttons aren't mapped as they were before making that change. MSX Video Mode is the only change i made. odd...

if i put it back to NTSC and resume the game, the music is sped up but i still don't have control of the game character. i have to exit the emulator and relaunch the game to get my controller mapping back. is this as expected?

@Thorr69 thanks for the reply; i didn't know about that setting and thank you for sharing, but that's not what's going on in this case. some games for the msx just have the buttons swapped from what you'd expect, like Vampire Killer, as mentioned in the video linked below.

i have a few solutions for swapping a and b now for this emulator, but now i'm focused on mapping keyboard keys to buttons in lr-bluemsx (or adjusting the emulation speed in lr-fmsx), which i'm still hoping to figure out.

this video mentions that the buttons are swapped from what you'd expect in Vampire Killer even if you're playing on an actual msx with a controller (mentioned at timestamp 4:35, which i tried to include in the link):

Note that this setting might slowdown the emulation for some systems. If this works to fix the core loading issues, then you should add this setting only in the respective systems' retroarch.cfg, i.e.

/opt/retropie/configs/msx/retroarch.cfg /opt/retropie/configs/x68000/retroarch.cfg

while keeping the video_threaded="true" in the main configuration file to be applied to other systems.

Another thing you can try is to use the retroarch.cfg.rp-dist file instead and see if replacing the (long) retroarch.cfg with it would still make the bluemsx and px68k cores to crash.

I tried a lot.

There is a SDSnatcher rom without SCC that will work.

@boomspar Generally BIOS and ROMs are not provided by RetroPie unless there's free/open source. That's why the BIOS requirements are always mentioned on the emulator's page. Just like for ROMs, you're responsible for copying the necessary BIOS files in place - they don't come with the package installed from the RetroPie-Setup.

I just found another one. I just copy the description from my other topic.

Arcade / Mame2010

Puzzle Break
pzlbreak.zip
This is a modern Arkanoid like game, with 2 player simultanously option. It looks quite nice and plays well with regular joystick. The special thing about this game is, the player can bounce the paddle's right or lift side up, so the ball will fly in this direction. That allows for greater control.

Nevermind, I got it working. You have to choose the fbalpha neocd option before loading. Also, it looks like it doesn't have chd support and no cd music..which was the point of using this. Thanks anyways. Back to lr-mess.

Got it .

Thanks

@edmaul69 it does work but just normally, like bluemsx, and with crappy sound. In BlueMSX pc version of the emu, you need to choose MSXturbo in order to get the hack working, so i thought it would work just the same as that :/

I looks through the romset, and there are around 200 individual games in disk format marked as British releases, so assuredly in English. All of the cartridge games were either in Japanese or Korean.

I did a bit of reading up, and many of the games were converted from Sinclair Spectrum versions, as the hardware and graphics capabilities were fairly similar. The games list I looked at seemed to confirm it - lots of classic spectrum games.