Just as the stars shine with complex and diverse brilliance in the night sky, so too might the thinking process of a human brain be described.

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The CEO's proposal to completely eliminate the marketing department in one fell swoop was, not to put too fine a point on it, a bridge too far for the board of directors, though their latest quarterly earnings, while not too shabby, certainly weren't stellar (?) enough to warrant such drastic measures.

Not sure stellar is the adjective you're looking for. Cutting a whole department sounds like something you'd do under financial distress, but stellar is a very positive adjective.

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The debate about consigning the controversial land development project to the history books was, to put it mildly, out of bounds even for the most seasoned politicians who had been around the block a few times.

Again, grammatically this is fine, but I'm not 100% sure it's conveying the intended meaning. As written it sounds like it would be unacceptable to the politicians to discuss shutting down the development project. But if the development project was controversial, you'd expect the idea of shutting it down to be something the politicians would at least discuss.

In the teeth of public outcry and short of exigent circumstances that might have swayed opinion, the mayor, far from being the prettiest belle at the ball in this situation, found herself increasingly becoming a Debbie Downer as the festering discontent threatened to boil over.

There's a lot of metaphorical expressions in use in this sentence, and some of them are very formal/academic in tone (exigent circumstances), some of them are very casual (debbie downer), and others are a little archaic (prettiest belle at the bell), so it makes the overall tone of this sentence sound a bit all over the place.

Her argument that the project was on the cusp of bringing unprecedented economic growth was a complete non sequiturly unfounded, and certainly didn't endear her to the increasingly hostile crowd.

non sequitur has some implications about how the argument follows on from the previous evidence, but that previous evidence wasn't mentioned in this piece, so I think it's better to simply say it was unfounded (lacking evidence).

"Alea iacta est," she muttered under her breath, a sentiment that didn't go down well with the protestors who felt she was in the tank for the developers.

I actually had to google "in the tank" myself. I think it's specifically an American English phrase.

On that note, and with the atmosphere growing increasingly tense, she decided it wasn't the right time to make their acquaintance, as iconsult with the crowd, thinking the negative effects of the development couldn't happen to a nicer group of people (sarcastically, of course), and ordered security to fetch her car, feeling that any further discussion would be bad, not even on par with a civil disagreement.

"make (pronoun) acquaintance" is primarily used for first time one on one meetings. Since the character in this story is the mayor, presumably she would be known to the protestors, and since she's not meeting them 1:1, it's not really a good use of this phrase.

"it" needs the topic previously introduced and it wasn't really here.

This sentence in general is just trying to do too much, and so would probably be better split into 2-3 sentences.

Just as the stars shine with complex and diverse brilliance in the night sky, so (too) might the thinking process of the human brain be described.

(omitted) ¶
The CEO's proposal to completely eliminate the marketing department in one fell swoop was, not to put too fine a point on it, a bridge too far for the board of directors, even though their latest quarterly earnings, while not too shabby, certainly weren't stellar enough to warrant such drastic measures.