Navigation keys were excluded from the orange pack as a design choice.
With the inclusion of windowed Caps lock, Scroll lock keys, as well as compatibility support for a variety of popular layouts, the reverse set is already a lot larger than most modpacks.
If the navigation keys were to be included in the reverse set, then the navigation keys for 1800, 75% should also be included (otherwise it wouldn't look right to include TKL nav keys but not for the other layouts), and while we're at it, might as well add the numpad keys, adding up to a total of 14 extra keys. Hope that clears things up
Likewise, numpad users are a bit rare, but a numpad enter was still included, so it would look really nice either way. The add-on is really desiged to add a splash of colour to the set.
Also, I really like how evenly spread out it is, going from Orange to Charcoal then back to Orange in each major section.