Hey MartyMacGyver, thanks for the excelent photos in your posts!
I do sometimes source the double-row SMD headers from different suppliers, hence the slight differences in height that you noticed here.
The key is this: After you solder them onto the BX board, it shouldn’t matter much if there ends up being a little bit of space between one of the header’s insulation and the breakout, especially since the header will end up being soldered solidly to both boards. There will definitely be some space between the insulation on the outer rows of through-hole headers. Does this make sense?
In any case, I’m always happy to send replacements if any of the components are missing, broken, or wonky. Just let me know
Finally, I’m planning to update the datasheet with specific assembly instructions soon. In the meantime, it might be helpful to check out the assembly instructions for one of my Teensy breakout kits, since the concepts there are extremely similar, and the BX kit assembly is overall simpler.