I had someone explain to me once that 7 is several because that’s what it says in the bible.
Okay, that’s new to me. 
I use few to mean two or three in a context when I am trying to minimize “I made a few mistakes.” and several to mean two or three in a context where I’m trying to maximize *My oppponent made several mistakes.”
Yeah, I didn’t want to get off on that side discussion, but my use of those words is like yours. Same with stuff like “couple” (it’s not literally two most of the time, but it can be). There’s a range of amounts all those words can convey and they’re not fixed concepts in my head and very much context and intention dependent. “Oh, yeah, I had a couple beers at the bar.” ← that could mean pretty much any number. “I’ll get back to you in a couple of days” ← Two to four, maybe. If I wanted to be specific, I would say “two.” Same with the words you cited. These words have a lot of “fuzz” around them. There is a loose hierarchy, though.
I’m quite strict about a couple being two and only two, but few and several do have contextual flexibility.
I’ve been in similar positions for most of my working life, but I had managers who would regularly throw me under the bus and take the side of the people complaining, so I guess I never really got to grow a thicker skin
It’s racist, sexist, socially divisive, dismissive of minorities, lacking in common sense, workplace inappropriate, theologically problematic, unapproved, non-certified, potentially actionable, fiscally irresponsible, technologically unsound, possibly illegal and a threat to all people everywhere.
Somehow I don’t think my personally not using the word “niggardly” or “niggling” is going to change the course of the English language.
And I’m not at all worried about a “slippery slope”, nor of running out of words. Language changes. There are lots of new words every year, and old words acquire new meanings.
“master bedroom” does not actually use a definition involving human superiority and power. The same definition is used for the “master cylinder” in a brake system; the cylinder is not human, it exercises no social or psychological power, but it is in control of the whole system; what it does, the individual cylinders have to follow. Now, I can understand an objection to calling those smaller cylinders slaves, even though this use of the term is well established in mechanical terminology. “Slave” is itself a fairly offensive term, which “master” is not, in and of itself.
The elephant in the room, I feel, is how willing people have become to project offensiveness onto previously neutral terms. This is not an academic question. If we were to totally eradicate the word “slave” from English (along with the euphemistic “enslaved person”, etc.), we would be left with no word with which to discuss the history of forced labor in, say, ancient Rome. With no way to discuss it, we would be doomed to repeat it, as the saying goes.
IMHO, as the son of a linguist (that’s SOL for short), all attempts from the “top down” to make language inoffensive merely antagonize someone, leading to more negativity. Look at any ultra-right blog, and you’ll find that the 1970s attempts to change “manhole cover” to “person-hole cover” are a primary source of anti-left-wing complaint. I’m not being partisan here; much of my anger as a left-leaning thoughtful person focuses on the Right’s weaponization of words like “woke.”
Simply put, language doesn’t work by decree. It evolves. Trying to stand against the tide is futile, yet paradoxically, when gentler persuasion is used to change the thinking behind words, the language tends to follow. Think, for instance, of the original outcry against “Ms” which has by now become almost universal, because women provided a convincing rationale for the change, and a manageably simple alternative term.
It is well known that adults, and even teenagers, have an almost impossible time learning a new language; our brains tend to harden in this regard, some time after puberty. Ordering someone to change the terms they grew up with ignores the fact that language change is gradual, evolutionary, and for most of us quite difficult. To the extent that we want to make our language more thoughtful and humane, we must start from a position of patience and persuasion. It can be done, but this is an arena in which too much force results in long-lasting backlash.
In my experience euphemisms are used to decrease the impact of words/phrases.
AIUI using enslaved person instead of slave is an attempt to increase the impact.