If the button is recognized by EmulationStation, then it should work in any Libretro cores - I think you're confusing the 'home key' (keyboard) with 'home button' (joypad).
Please add more info about your setup, as detailed in https://retropie.org.uk/forum/topic/3/read-this-first - including the exact controller type and model you're using.
This did not work for me. If it is just my install, then I am fine, but may want to mention the other location in the docs, since it is what is mentioned in the info file I mentioned above, and it does work in my case.
The 'other' location from the .info file refers to the BIOS files, not the samples. Same info from our docs is found also in the official core documentation. Note that RetroPie configures the 'system folder' to /home/pi/RetroPie/BIOS/.
If you have reset your RetroArch configuration - using the Reset menu in RetroArch - then the 'system folder' is empty and defaults to the ROM folder, which might be your case.
The purpose of those vintaged cores was to be snapshots of how the concerned emulator was back in that year, amongst other thing to guarantee the romsets don't change and to prevent the performance regressions coming from bugfixes. Well, i recently learnt that the situation might be more hazardous though, but i don't think retropie is auto-updating so i suppose your issue is elsewhere.
@jamietuley my first question is if this a RetroPie build image or did this come from something else. Honestly, hissing is something I've never had an issue with with any of the 4 Pi3bs I own, nor was it a problem with my Pi2 before.
I don't know why you would have needed to alter any config file for the sound. It's better not to play around with any of the base configs and just use the menu to turn things on and off. You can try the Raspi-config menu and see if anything regarding sound is not active. But I think the Audio selection in the RetroPie setup does the same.
Anything above that is above my skill level. I've not experienced the issue you're having, nor did I have to play around with the config file to get anything to work. I used the menus only.
@dankcushions Thanks, resetting the configurations tools > emulation station seemed to help for emulation station, but as you explained that doesn't clear out any emulator-specific configs.
I know you said deleting .cfg files was a big no-no, but I deleted the rom name specific config files in the folders within
(but ONLY those named the same as the game ROMs)
EDIT: and now my arcade games that were going wonky are functioning correctly! NOW I need to get back to figuring out how to assign the spinner to tempest for example, without messing anything else up.