While I did notice some support for the space belts, there is actually a higher tier of them called deep space belts. Additionally, while they start out black, there are recipes for them to change their color, and this includes the deep space underground belts.

Each color variant does have a startup setting to determine if that color is available or not. In this case, the setting name that you can check is the following, for each of the non-black variants.
"se-deep-space-belt-white"
"se-deep-space-belt-red"
"se-deep-space-belt-magenta"
"se-deep-space-belt-blue"
"se-deep-space-belt-cyan"
"se-deep-space-belt-green"
"se-deep-space-belt-yellow"

Tech name is "se-deep-space-transport-belt"

In this case, the internal names for the deep space belts and all their variants are
se-deep-space-underground-belt

Underground recipe names:
"se-deep-space-underground-belt" - The base recipe does NOT have the -black suffix for its default variant.
"se-deep-space-underground-belt-white"
"se-deep-space-underground-belt-red"
"se-deep-space-underground-belt-magenta"
"se-deep-space-underground-belt-blue"
"se-deep-space-underground-belt-cyan"
"se-deep-space-underground-belt-green"
"se-deep-space-underground-belt-yellow"

Underground entity names:
"se-deep-space-underground-belt-black"
"se-deep-space-underground-belt-white"
"se-deep-space-underground-belt-red"
"se-deep-space-underground-belt-magenta"
"se-deep-space-underground-belt-blue"
"se-deep-space-underground-belt-cyan"
"se-deep-space-underground-belt-green"
"se-deep-space-underground-belt-yellow"

Item names:
"se-deep-space-underground-belt-black"
"se-deep-space-underground-belt-white"
"se-deep-space-underground-belt-red"
"se-deep-space-underground-belt-magenta"
"se-deep-space-underground-belt-blue"
"se-deep-space-underground-belt-cyan"
"se-deep-space-underground-belt-green"
"se-deep-space-underground-belt-yellow"

While these deep space belts are already made for same tier belt braiding, of course, why not be allowed to also braid in same tier AND color.

lol, I had these belts coded and was frustrated by not finding the recipe for black... doh.
I thought well, since they are all same speed, not much need. I had not thought to consider the color. I will add the support, looks like you solved my riddle! Although, since this will create quite a few recipes, I will likely make a startup setting, let folks choose to include these or not.

Regardless, the black braidy deep space belt should always be enabled, since it is possible that the player has ALL of the color options turned off, and as a result, would not be able to use any color variants for belt braiding purposes.

New version available which adds deep space braidy belts.