Are there any strategies that can augment this for making writing that sounds more authentic and less "thesaurus-y?"
In Non-Fiction: I don't believe there is a strategy, because "authentic" speech is just not filled with words that people must run to the dictionary (or pop up a dictionary on their phone) in order to understand. If you use words that 90% of people do not understand, that doesn't sound authentic, that only sounds pretentious.
For many it is actually annoying because it sounds abusively pompous and elitist, as if the speaker considers themselves above the common class.
I can use a thesaurus as well as the next spelling champ that spent twelve years in college, but the point of writing (non-fiction) is to communicate ideas, and the more words used that readers don't understand, the more opaque the writing, and the less your ideas are communicated. An occasional thesaurus word that is semi-defined by context (e.g. it is an insult, or praise, or term of frustration) can add spice, the meaning is not lost. "Oleaginous" (oily, greasy, slimy) was recently used in an editorial describing a distasteful person and made quite a stir, becoming a Google most searched term for a day. But the rest of the article it was used in was NOT written using words that had to be searched, so it served its purpose as a highlight.
In marketing (one of the fields I have studied outside of college), there is an aphorism, "If you highlight everything, you highlight nothing." Meaning if you highlight, bold, italicize, underline, box and enlarge things all over your advertisement, a reader's attention will not be drawn to any of it, it just makes the text difficult to read so it gets put down. But if you put a box around just one sentence on the page, you can be pretty sure people are going to read that one thing.
This applies to thesaurus words as well; if they are used sparingly, they make the prose better. But, like any spice, if they are overused they will overpower the dish and ruin it. some salt can make a dish better, too much renders it inedible.
You can have a pretentious character in fiction if they are accompanied by at least one non-pretentious character. The frequent use of rare words is often used as an indicator of high education, or pretenses of a high education.
Elaborate speech to the point of opacity is also often used as a shield for the emotionally insecure, as if appearing to be of high social station, highly educated or of high intellect will win them a measure of respect and deference. In a similar sense, ornate words most people cannot easily define are often used to dress up otherwise boring or trite ideas (William F. Buckley Jr. pops into my head for some reason). Both of these are a type of fraud (inauthenticity) and part of the reason such speech is often disdained.
Nevertheless, knowing this is how they are perceived will let you develop fictional eloquent characters, and in fiction we can see their true nature and why they find it important to speak thusly.
As a general rule, don't send your readers to the dictionary very often, and if you use words that probably would to occasionally highlight something, it is best to use them when the context suggests at least the general category of the word; don't make the sentence unintelligible if the reader doesn't stop to look it up.