Do you think the dialog is made by native English speakers? If not, polish it.

A: You've been such a big help to me! buddy, I really appreciate it!
B: Be my guest. that's what a buddy-buddy for.
C: But, you know, I am just so grateful!
D: well, I'll be unhappy if you keep saying that.by the way, you are very skillfully experienced.
E: You are flattering me. Brother.
F: No need to be humble. you are second to none within the radius of dozens of miles around.
G: In fact, I know nothing. really.
H: you brother are really a modest type!
Depends if you want British English or American English (then an American can comment!)

A/B Buddy is not really British.

D 'skillfully experienced' makes no sense. You can be skillful or experienced, but this phrase means they are very good at being experienced!

F you are the best for miles around

E/H Brother again does not ring true for British English.

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May I try, Jobb?

A: You've been such a big help to me, buddy! I really appreciate it!
B: You're welcome. That's what friends are for.
C: But, you know, I am just sooo grateful!
D: Well, OK. Just don't keep saying so. Anyhow, you're pretty experienced in this kind of thing yourself.
E: Now you're flattering me, brother.
F: No need to be modest. You are hot, brother. Second to none.
G: I don't know ***. Really.
H: You are so goddam modest!

BrE alternative version:

A: Um...Thank you.
B: Not at all.
A: Very decent of you.
B: Don't mention it. Anyway, you weren't so bad yourself.
A: I don't know about that.
B: Not bad at all, in fact.
A: Oh, it was nothing.
B: Good Lord. Did you see that? All out for 91. Pass the marmalade, there's a good fellow...

Thank you.

But what is All out for 91.?
Students: Are you brave enough to let our tutors analyse your pronunciation?
I think it's a 'cricket' reference. He must be reading the paper. It is quite English to change the subject when you're being thanked for something.

Re: Interesting, MrP

Jobb, I commend your usage here.

Thumbs up.