That seems to be covered in this thread…
The disp_cap file I was referencing is just a text file placed in Kodi’s userdata location that contains a list of the supported output formats. My understanding is that when present Kodi will ignore what information is received (or not) from the display and use what is in this supplied file instead. I don’t think that command to create the file automatically works on Rpi’s, but it works if you manually create one. I suppose @grahamh can correct me if I’m mistaken on this point.