Are these actual errors?

[Cyndi Morley-Perez]

Unfortunately I don't think any of these are errors except short lived. Can anyone advise me?
1) In my actual review, I did italicize the title but it's not showing here.
2)begins with retired investigator” should be “begins with a retired investigator”. This is wrong because I use his name after it. It is not an investigator. It is a specific investigator.

** the rest are just comma errors that are supposed to be stylistic.

Editor Comments:
Precision by D.C. Scott. begins with retired investigator, Jay Macgruder, reopening a cold case that piques his interest due to the fact that he knows the victim.
—
“Precision by D.C. Scott.” should be “Precision by D.C. Scott”
—
“begins with retired investigator” should be “begins with a retired investigator”

What could fall in the romance category if written differently, becomes just a flat retelling of a life story by an acquaintance.
—
“romance category if written” should be “romance category, if written”

But on the other hand, it was in no way my idea of a murder mystery, as the mystery only came at the end and was very short lived.
—
“short lived” should be “short-lived”

[Diana Lowery]

Unfortunately I don't think any of these are errors except short lived. Can anyone advise me?
1) In my actual review, I did italicize the title but it's not showing here.
2)begins with retired investigator” should be “begins with a retired investigator”. This is wrong because I use his name after it. It is not an investigator. It is a specific investigator.

** the rest are just comma errors that are supposed to be stylistic.

Editor Comments:
Precision by D.C. Scott. begins with retired investigator, Jay Macgruder, reopening a cold case that piques his interest due to the fact that he knows the victim.
—
“Precision by D.C. Scott.” should be “Precision by D.C. Scott”
—
“begins with retired investigator” should be “begins with a retired investigator”

What could fall in the romance category if written differently, becomes just a flat retelling of a life story by an acquaintance.
—
“romance category if written” should be “romance category, if written”

But on the other hand, it was in no way my idea of a murder mystery, as the mystery only came at the end and was very short lived.
—
“short lived” should be “short-lived”



RE: This sentence - The editor is correct.
What could fall in the romance category if written differently, becomes just a flat retelling of a life story by an acquaintance.

The subject in the sentence is the noun clause at the beginning (What could fall in the romance category).
The verb is becomes.
You cannot separate the subject from the verb with a comma.
You can set off the phrase (if written differently) with the two commas, or you could eliminate the commas altogether, but the original sentence is incorrect with just the one comma.
It is not stylistic. It is a basic grammar rule.

[Cyndi Morley-Perez]

Ok, I agree with that one. I just find it very difficult to decide whether or not to use comas here, because in other reviews I've been told not to. If I wrote with all the comas I've been taught to use in school, the editor takes them out. Thank you for your help. What do you think about the other errors?

[Diana Lowery]

Ok, I agree with that one. I just find it very difficult to decide whether or not to use comas here, because in other reviews I've been told not to. If I wrote with all the comas I've been taught to use in school, the editor takes them out. Thank you for your help. What do you think about the other errors?

RE: This Sentence :
Precision by D.C. Scott. begins with retired investigator, Jay Macgruder, reopening a cold case that piques his interest due to the fact that he knows the victim.

Obviously, the period after Scott is an objective error.

The commas you placed around the appositive show that it is nonrestrictive, meaning that the phrase could be removed from the sentence and the sentence would still be correct. In that sense, the article is needed.
If you had written the sentence like this, . . .begins with Jay Macgruder, retired investigator, reopening. . .
then the sentence would be correct without an article.
If you had considered the appositive to be restrictive and used no commas, then the sentence would be correct without an article.
Here is a link about appositives:
https://www.scribbr.com/nouns-and-prono ... .%E2%80%9D
I hope I have not confused you even more.