I "corrected" that blob without really noticing it because I had already decided the schematic was more a guide than a definitive reference
One version of the schematic I used had the numbers for the common cathodes of the display backwards and guess which one I followed on my initial prototype! So when I finally got my prototype working the display was fully working and backwards! Much track cutting and bodge wire fitting followed that one.
All things considered its a wonder I got the keyboard connector correct as I seem to have done. I think its because by then I was using an issue V schematic I'd found and confirmed it with posts I'd seen on here (possibly your MK14 uploader device). Because the schematic was so vague I had to go looking elsewhere...