> The original sentence was a little confusing:  "To get a list names
> ever exited in monthly worksheet."
> 
> I changed it to: "To get a list of all names ever exited in each
> monthly worksheet."

You failed to identify that **exited** isn't the correct word grammatically.  The author was looking to use **existed**.  Even the correct word, that the author meant to use, is a poor word to use which means a different word should have been suggested (i.e the word *created*).  You failed to correct all grammatical mistakes in the answer.

> I think it's much easier to read if it uses correct grammar, especially because I made sure not to change the original **intent**.

I don't agree with your conclusion.  You failed to address even half of the grammatical mistakes in the answer.

> Again, you may need formula like `if(isna(vlookup(...)), "",
> vlookup(...)` to get rid of the `#N/A` text when a given name not
> found for some specific months.

You failed to identify the grammatical mistake in this sentence.

> Again, you may need **a** formula like `if(isna(vlookup(...)), "",
> vlookup(...)` to get rid of the `#N/A` text when a given name not
> found for some specific months.

> Once the *full name list* is got, later monthly update can be
> appending name list from new monthly to *old full name list* then
> re-filter it.

You failed to identify the grammatical mistake in this sentence.

> Once the *full name list* is **determined**, **future** monthly update**s** can be
> **append the name list from the previous month's list and then re-filter it.**

> From a database's point of view, this is in fact to get a union of
> name lists in monthly worksheet (including removing the duplicates);

You failed to identify the grammatical mistake in this sentence.

> From a database's point of view, this is in fact to get a union of
> name lists in the monthly worksheet (including removing the duplicates);