I have been following the exact steps as outlined in this tutorial video, with no oddities happening along the way: https://youtu.be/twQbHWJF7LA
Well, I was able to follow it up and until we got to the Partitioning part, where he says to load DOS up in the machine, presumably meaning the PC-10 in this case.
The PC-10 loads the ISA IDE to SD Adapter just fine, it even tried to look for Drive C (The SD Card) for like 10-15 seconds, until giving up then and there (as seen in the pic).
(ISA IDE to SD card Adapter i got:) 
In other words it seems that the Adapter either doesn’t recognise what is on the Card and I’ve done something wrong in burning the provided image onto it or formating, or it doesn’t recognise the card itself to begin with. Its a Brand new 32GB SanDisk SD so that be pretty suprising…
In other words… im out of ideas… i tried different DIP switch configurations and all, but no change. Perhaps the PC-10 III Simply doesnt like the Adapter… or can’t run 6.22… im just out of ideas and frustrated. I’ve had this thing for over a month now with no luck in seeing it run once properly, and original 5,25" DOS Bootdisks are expensive and take a while to arrive. Should I just bite the bullet and go for one? I don’t know. Any advice is much appreciated…
DOS disk interface is quite mundante. It was dependant on BIOS recognition, and its not compatible with 32 GB disk at all. An 120MB or 250MB HDD was the usual MS-DOS disk sold during the 6.22 era. The firsts GB disk ware common by 1996. By the way, 2GB is the max recognizable partition size. Use fdisk to create a Master Boot Record, and a 2GB partition, and try it. I tried it with ease with old 1 GB and 512MB Compact Flash cards, but I must say CF has almost direct compatibility with IDE. SD cards require an adapter controller (you seems to have one of those, tho).