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.