It's so stupid complicated. There's no reason for it.
For crying out loud, Cova and Leia already works. Why does she just have to work with R4 as well? It's too much and will be totally busted. There are two ways this could go:
1. Cova is always taken with R4 and is so good she needs a 5 pts increase, and because of that she is never not taken with R4 (it's cheap and there's no room for Leia), so the Astromech slot is no longer an option; your decision is made for you
2. R4 gets stuck with a few points increase (which is entirely unwarranted except in this mind-bogglingly wrong case) and is suddenly hardly playable on anything except Cova. And at the same time, it's not enough of a nerf so Cova is still the only transport pilot flown.
The whole thing is just stupid.