Holy sh...! It's alive again! I cannot pin the reason down though, but I'm certain it was something I made wrong again and again. Maybe sth. to do with the windows ssh shell (didn't want to set putty up because I find that confusing). Anyway, thanks so much for guiding me through. 
@jonas hey there, since I am not expecting anything to change I've installed DragonBlaze v6.1.1 onto the SD Card.
I had to struggle with the Arcadeforge setup there the last time, but had it working.
BUT NOW it seems all info on how to do this is gone, since I cannot find the wiki anymore (for recalbox v6 or earlier).
This is what I have done:
recalbox config
This is what I have done via putty/shell:
done that by:
mount -o remount, rw /boot
cd /recalbox/share/system/configs/xarcade2jstick
touch usb-Arduino_LLC_ArcadeForge_Key_Strike-if02-event-kbd
That should be 99% there, but I guess I am missing something, because when I try to do the controller configuration (where you have to hold one button to start configuring the device) it says "keyboard" and I am pretty sure it said something other than that the last time (months ago though).
Tried everything back and forth, checked the ArcadeForge button binds, tried it in gamepad mode and so on... with or without rom library on external USB HDD.
Cannot get my 2-player joystick/button combo to work. Which is pretty sad. Sure, I can hook up PS3, PS4 or 8bitdo controllers (and many more), but I did not build a bartop arcade for that.
Anyway, rambling won't help either ^^
Do you remember or possibly have any notes on how to setup a keyboard encoder?
Thanks!
@Zing Hey there. Don't get me wrong, please - I am sure, everybody involved is doing their best to bring the project forward. And I know that your problem does not get recognized or pushed top priority just because you've reported it. No way 
On the other hand, if you (as a user) are stuck with something for months, more often than not with the added passion of a personal DIY project, it gets frustrating when there's seemingly nobody actively into solving it.
I think everybody does understand the pov of the users in this as well?!
@Zing Hey there. Don't get me wrong, please - I am sure, everybody involved is doing their best to bring the project forward. And I know that your problem does not get recognized or pushed top priority just because you've reported it. No way
On the other hand, if you (as a user) are stuck with something for months, more often than not with the added passion of a personal DIY project, it gets frustrating when there's seemingly nobody actively into solving it.
I think everybody does understand the pov of the users in this as well?!
@pssadm Thanks for describing your situation as well. I have put 2-digit hours into trying to solve the seemingly problem on my end (adding custom controllers wasn't too easy anyway) but I don't think it's something you could solve by doing it different anymore.
When I have the time and desire I will try it again with recalbox v6 - which wasn't successful the last three or four times btw but I had it working prior to upgrading to v7 - or I'll move over to some other project. At the moment I am still hoping for "the magic update that fixes this" but ...
Thanks! What could be the cause for the usb encoder to be only recognized as "keyboard" no matter what I try, though?
Flashed the 6.1.1 image fresh onto the sd card (removed any custom partitioning and so on beforehand), made basic configuration (like WiFi so I can get SSH shell connection), and tried creating the file(s) mentioned in the /system/configs/xarcade2jstick folder (file a, file b, file a and b).
Each try with a reboot and testing of course. Double checked using the exact same name the ls command is outputting, despite using copy and paste for it.
Only getting "keyboard" now when configuring the buttons, which is quite frustrating.
@jonas hey there, since I am not expecting anything to change I've installed DragonBlaze v6.1.1 onto the SD Card.
I had to struggle with the Arcadeforge setup there the last time, but had it working.
BUT NOW it seems all info on how to do this is gone, since I cannot find the wiki anymore (for recalbox v6 or earlier).
This is what I have done:
recalbox config
This is what I have done via putty/shell:
done that by:
mount -o remount, rw /boot
cd /recalbox/share/system/configs/xarcade2jstick
touch usb-Arduino_LLC_ArcadeForge_Key_Strike-if02-event-kbd
That should be 99% there, but I guess I am missing something, because when I try to do the controller configuration (where you have to hold one button to start configuring the device) it says "keyboard" and I am pretty sure it said something other than that the last time (months ago though).
Tried everything back and forth, checked the ArcadeForge button binds, tried it in gamepad mode and so on... with or without rom library on external USB HDD.
Cannot get my 2-player joystick/button combo to work. Which is pretty sad. Sure, I can hook up PS3, PS4 or 8bitdo controllers (and many more), but I did not build a bartop arcade for that.
Anyway, rambling won't help either ^^
Do you remember or possibly have any notes on how to setup a keyboard encoder?
Thanks!
Well, no progress on this one neither by myself or the devs so I probably will switch back to recalbox v6 or some other raspberry emulator distribution, I guess... Sad. 
@jonas Thanks very much for going through the hassle of testing this and writing down your findings. At least I am not the only one and can be somewhat certain that further fiddling around with settings, trying different bindings on the keyboard controller itself and so on wouldn't be successful neither. Don't get me wrong: I did this prior of posting in the forums/github bug tracker. For hours. Things like this, especially when it's a self-made and not too cheap thing, drive me mad. I want the stuff to be working.
Help from one of the devs would be very much appreciated. Whatever I am able to contribute: just let me (us?) know.
As a last resort I could always go back to the latest Recalbox v6, I guess ...
Bartop without the joysticks and buttons working is quite useless after all
Ok, thanks to Home Office I quickly flashed the 7.1.1 onto the SD Card and tried assigning the encoder. Same behavior as before, sadly.
When it comes to assign "down" it just skips that entry and assigns the down press (button 5 in my case) to the next one in the list. I continue to assign all other buttons and re-assign wrong assignments due to the skipping before but I am unable to assign "button 5" or anything other to "down".
When accepting this "joystick up" fires twice every time and "joystick down" not at all.
Could you please tell me where the input configuration is written so I can probably fix it manually in there?
@acris I've installed a fresh 7.0.1
Great that there's a 7.1.1 already, will try that later today and report back.
@jonas thanks for sharing your experience! Buttons work fine here as well, left/right of the joystick(s) as well, but up/down is always very finicky. Can't get them working properly, they always register nothing at all or double input.
Used the encoder since Recalbox v4 or something and had every release since then, worked fine with more or less configuration from time to time, but for v7 I'm currently lost.
Did you manage to get the encoder configured in v7?
also tried the button mapping mentioned here https://recalbox.gitbook.io/tutorials/usb-encoders/recalbox-for-your-usb-keyboard-encoder under Key mapping v4.0.0 - beta4
