I'd like it if the AI raid starships kept the current "mirroring" of stats they have to human ones currently, same in every way but HP, where the AI versions have 1/2 the HP.
Thus, if we want to buff human ones without touching AI ones, reducing knowledge costs seems reasonable.
Or, if we want to break the symmetry, we could remove AI raid starships (or at least that name for them), and give them a new unit named something different (so there is no expectation of symmetry), but serves a similar role.
Similar argument for the fortresses. Either keep the symmetry (which would include not only things like just adjusting stats and multipliers, but also things like splitting the fortresses into several different variants), or make the AI units called something entirely different.