I think all buttons other than the space bars are made by Topre, so any color differences would be very minimal, if any.
I'm not so sure about that. You see, it seems that there are two kinds of Topre red colors. One is of brighter shade, and the other is somewhat darker.
First would be:
- Limited Edition Control and Esc Kit
And in the second, darker red group, we found:
- complete Topre red keyset
- standalone Topre red ESC key
- standalone Topre red arrows keys
I only have a red Topre ESC key so I can't actually make any live comparison, but this is the information I got before on this forum, and judging from some of the images on the internet, it seems to be the truth. Red PBT spacebar rev1 really looks brighter and orange-like.

As for the bars, matt3o spent a lot of time color calibrating them. Not sure if they're 100% matched, but they're pretty darn close.
That's not the point.
In any case, these are your only PBT space bar options, so you have no other options.
I'm sure they will be pretty good, but it's just my OCD waiting its chance to go wild.

white and black are color matched with a 98-99% color accuracy (matched to hhkb colors). Red and blue are in the 95-96% range (matched to special edition kit). Orange and green should be 99% (matched to original topre sets).
I'm sure they are, but what I'm trying to tell you is - you've calibrated your spacebars using a wrong color sample, at least in the case of red.