Red dwarfs are theoretically habitable (if you want to ignore their propensity to flare, which in 3025 can be overcome with technology), and at any rate there are already 4 M-type stars on the map...if they were inhospitable, there would be zero. K-type stars are definitely habitable, being only slightly smaller than our sun, yet there are only 6 K-types on the map. On top of that, the system files mention lots of systems with no population. On top of that, the G-type stars ought to range in transit time between 6 and 10 days, yet the system files are ridiculously heavy with 9 day transits.
From Wiki:
https://en.wikipedia.org/wiki/Stellar_classification#Harvard_spectral_classification
This chart is for all visible stars, yet comparison with the 1,000 closest stars to earth is very similar so it's a good representation of our galaxy (or at least galactic neighborhood).
If there are about 150 systems in our game, according to this distribution there ought to be:
115 M-type stars
18 K-type stars
11 G-type stars
5 F-type stars
1 A-type star (though with enormous transit times involved, it would be fine if the developers omitted any types above F)
Now, an accurate portrayal would be awfully heavy in M-type stars, so I wouldn't object to having a lot fewer than 115. But there ought to be a lot more than 4! Maybe 20-50 would be fine, and increase the K-types to 30. Then, make sure there's a spread in the G-types, with an even number of 6, 7, 8, 9, and 10-day transit systems. There's no reason every one of these G-type stars should have a transit time exactly equal to the Earth's!
This should be completely do-able, as I surveyed about half the systems in Sarna.net, and there's only canon spectral types listed for about 10% of the worlds. HBS made up all the other info. As I stated, they even invented some new systems. Of the listed systems I found, there were 2 Ms, 2 Ks, 4 Gs, and 3 Fs. That's a perfectly reasonable ratio, rather than having 90% G-type stars.