Sure. I have to put my translation skills on the spot, which I am a bit self-conscious about, but I’ll give it a shot:
"Mostly, it might start from a mere feeling. But particularly, not only shinkeishitsu people* - for example, those who see a hearse, those who hide from ominous signs, those who don’t cut their nails at night – people do unexpected things."
* I understand shinkeishitsu but am not fully understanding of the meaning in this context. I understand it to be a sort of social neurosis that psychiatrists see as a condition in Japan. Sort of like social dysfunction (awkwardness). However, this particular part of the sentence I am not particularly concerned about.
"xxxx, It might start from a mere feeling. But particularly, not only shinkeishitsu people* - for example, those who see a hearse, those who hide from ominous signs, those who don’t cut their nails at night – MOST people do unexpected things."
Your translation of the second sentence is still quite a bit off. Step back and look at the overall structure of the sentence, making sure that you are parsing it correctly. In particular, note the TWO occurrences of したり, and make sure you know the purpose of と in 見ると. Then make sure you correctly identify precisely which portion of the sentence modifies the final 人. Finally, to get it out of the way, go ahead and translate 神経質な as 'high strung', 'nervous' or 'neurotic'.
I encourage you to keep at it with this sentence. Figuring it out by yourself, with our gentle hints, is a good way to learn Japanese (and the Japanese way of communicating, which is quite different from English). That second sentence is a good practice sentence.
Hmmm. I will give it another go. This is a typical problem of mine that when there are too many grammatical features, I kind of lose track of them in my head.
But especially, not only neurotic people, [? There has to be a better English gloss for this construction that I’m not getting], many people will do things such as hiding their thumbs or not cutting their nails in the middle of the night to avoid sinister luck if, for example, they see a hearse.
You missed 案外. As I wrote above, 特に modifies 神経質な. Grammatically, it's possible to interpret that 霊柩車を見ると is a conditional clause for both the following two clauses, but actually 霊柩車を見ると is only connected to 不吉そうに親指を隠したり. Thus, the two listed examples are 霊柩車を見ると、不吉そうに親指を隠したり and 夜中に爪を切らないようにしたり. On the other hand, 例えば modifies both examples.
In terms of grammar, "modifies" just means describes / connects with / pertains to. So by saying that 例えば modifies both of those clauses, it means that it connects to each of them. Or, in other words, each of them is being cited as an example. But you already have figured that out...
You may remember from English class that most adverbs end in "ly". That's true of the adverb being discussed here, too.
Your most recent attempt at translation was actually not bad at all. Here's one more hint: Part of the second sentence is structured like this: (.........A........)人はB. What this means is that first the sentence describes a certain type of person (A), and then it says something about such people (B).
"Not just neurotic people, but many people unexpectedly do things, such as if they see a hearse, hide their thumbs to ward of sinister luck or not cut their nails in the middle of the night."
I have been looking the sentence over and the best thing I can come up with is this. However, this is not significantly different from what I previously had. Regard the A人B distinction, I tried to follow it but it also seems like I had something like that before as well.
You missed 特に. You still misunderstood 案外. As Mike-san gave you a hint 案外（多く）いる, 案外 modifies （多く）いる, not している. と conditional expresses habit or repeatedly occurred things, so "when" is more appropriate there. The biggest mistake you did in your initial translation is the interpretation of 霊柩車を見ると. This is completely different from your newest one.
The 特に I am having a hard time grasping. If I translate it into English literally, it seems to yield something like the bold. However, it seems to not sit right in English, so I am thinking there is probably a better gloss that would make sense, which I am not arriving at. I think I changed the position of 案外 to modify the 多く
"But especially, not just neurotic people, but unexpectedly many people do things, such as when [not if] they see a hearse, hide their thumbs to ward of sinister luck or not cut their nails in the middle of the night."
Edit follow up question: でも特に, might that gloss to something in English like "But uniquely" or something that is sort of unexpected in nature?
"But not just neurotic people particularly, but unexpectedly many people do things, such as when [not if] they see a hearse, hide their thumbs to ward of sinister luck or not cut their nails in the middle of the night."
That was the gloss I was not getting. That makes a lot more sense. So ultimately:
"Not just excessively neurotic people, but unexpectedly many people do things, such as when they see a hearse, hide their thumbs to ward of sinister luck or not cut their nails in the middle of the night."