I should have been a little clearer on my suggestion — the idea being that the user can put them in whatever order they like, and use the different colours to know what key does what without really thinking about it (as opposed to associating a number with an action, which to me seems more difficult to remember. I'm basing this thinking on how good people are at recognising and remembering distinct colours). Thinking about it now, I realise that it's probably only me that wants this!
Just a quick note here: Cherry R1 profile works as a uniform sculpt in this context. It's one of the advantages of Cherry over sculpts that use a sharper curve in the F1-12 row (e.g. SA, MT3, etc.). Any standard Cherry set's F1-12 keys will look just fine in a columnar macro pad setting.
An all-R1 board isn't necessarily fun to touch-type on, but aesthetically and tactilely, it works fine for small clusters of keys (particularly when they're separated from the main clusters).
All this is to say is that a uniform macro column GB isn't needed, as that's already possible with any GMK set.