To compare:

Thanks for the feedback, I really appreciate you spending the time on these finer details I would not normally catch. Changes have been made, please see the attached.

Thanks for the feedback. I really appreciate you spending the time on these finer details I would not normally catch. Changes have been made. Please see the attached.

Both constructions seem off to me. DISCLAIMER: I am no editor or academic, I often face this problem myself and I eschew all sorts of concrete "rules" about "things." That sentence wants to be a joke. I meant to say I play it by gut. Specifically, by action.

(As I write, I reflect upon my own inadequacies. I reflect upon my own editing process, how crazy I get without any anchor and how I can now see why grammar would be useful, maybe not as an anchor which I doubt can exist in any positive way but as a buoy to hang onto against the enveloping ocean of aesthetic doubt. I reflect upon how hard that sentence might have been to get through. The ocean is cold and horrifying.)

I think if those sentences seem choppy or primitive, then he shouldn't write them. Just because they are childlike, does not mean that the commas are correct.

I think you're right. The problem seems obvious in approaching the action of the language. Thanks for the feedback, and I really appreciate you spending the time on these finer details I would not normally catch are two redundant thoughts, the second clause echoing the first while elaborating yes, he knows what feedback is basically.

Thanks for the feedback. Changes have been made, please see the attached.

... reads to me without problem. Gets it done without the layer of awkward insecurity. Now, as a grammar noob, have I missed the comma splice as inappropriate construction? Let me play the smarmy student that cannot help but push back against abstracted authority! I say no! I'm operating by rhythm here! A period creates a heavy space. A semicolon is too heavy but in a different way. A comma, a comma seems just right. That skip in mental processing that I like; that casual flippancy towards grammatical institutions which establishes a tone of conversational intimacy.

Maybe. I'm no expert. I'm not even sure I struck the right tone here. Maybe that comma splice is totally cool. Then I'd feel dumb.

If I may ask, why the SELF-DOUBT? Is it because his original sentence better hides his inelegance of action?