emsr2d2 here is a quote from your post
Then you use "do" in your dialog example.
That appears to imply to me you are suggesting this was something where American English that normally uses "take" instead of "do" cannot be used.
I showed that "take" works just fine.
I don't see how you reached that conclusion. The original question was "Can we say "do a course"?" (my paraphrasing). The first few responders indicated that "take a course" would be preferable in their variants.
The gist of the posts leading up to the one you quoted are:
Post 1: "Can we say "do a course"?"
Post 2: Native English speaker (but not BrE, AmE or CanE) says "Yes".
Post 3: My corrections to post 1.
(Post 4: Side question about "do" meaning study.)
(Post 5: My response to post 4 only.)
Post 6: AmE speaker says "Use "take", not "do"."
Post 7: CanE speaker says "Use "take", not "do"."
Post 8: Another AmE speaker disagrees with "do" and suggests that "take" should be used.
Post 9: I take the opportunity to make it clear that in BrE the use of "do" in post 1 is "absolutely fine", as it is.
I entirely accept (and said as much) that in the other variants "take" is preferable and I said that you will also hear "take a course" in the UK.