Your first screenshot seems to indicate you have a too low texture size set, because the textures are more blurred than they are supposed to be.
As explained many times (too many times), KIAH was designed in a very particular time, when there was no 64 bit simulator on the horizon, and we were unfairly accused to "cause OOMs" with our previous scenery, CYVR, which still looks good today, even if it's older than KIAH.
So, we made KIAH to be as lightweight as possible, because we always listen to customers and the result is, of course, the scenery if BY FAR the one that had less support issues. Of course, there's no free lunch and, what you gain in reliability, you lose in graphic quality.
No, it's not easy to change a scenery which has been designed in a certain way, and night textures are kind of special case, because they are inherently worse than day textures, unless you use dynamic lights in P3D4 but then, in order to do that, you'll have to redo the whole night texture from scratch, because adding something which was made for static light will look very wrong with DL on top of it.
So yes, we know night is not a strong point in KIAH, and this is precisely how the scenery was designed so, it's confirming to its design specs.
Of course, since we sell it in Trial version, like all our products, it's up to user to decide if the asking price is correct, all considering.