Oh wow, that goes in depth. I don't really use layers beyond shift, so I don't have an opinion on that.
(and tbh, whoever wrote that is pretty judgy, I would NOT want to use their "fixed Czech" layout)
We definitely prefer QWERTZ.
I originally ordered (UK) ISO with a split right Shift, so that'd be my adjustments beyond just the Czech layout as shown in the IBM pdf.
I couldn't find any photos of model Fs with Czech caps, and the Ms I found were not very clear, sorry about that.
So modern Czech kbs usually have (Z Y) on the Z and Y caps, with the default symbol in the top left corner. But neither of the Ms seem to have that. (so I wouldn't do that)
The older grey badge one seems to have secondary characters on some of the alphas, but not all that are shown in the IBM pdf. The newer blue badge doesn't have any that I can see.
I don't honestly care about those, but if we're going for accuracy, I guess we should stick to the IBM pdf?
edit: OK hold up, I might be wrong.
So I'm noticing that the beige secondary legends in the PDF are not how those keys actually work nowadays.
Should it be historically accurate to the IBM standard, or like..practical for today?