but also people in many countries around the world celebrate this day to enjoy Irish culture.

[sitifan]

Nowadays, not only do people in Ireland celebrate it, but also people in many countries around the world celebrate this day to enjoy Irish culture. (My bold.)
Source: Kangxuan
Can I rewrite the quoted sentence as follows?
Nowadays, not only do people in Ireland celebrate it, (but) people in many countries around the world also celebrate this day to enjoy Irish culture.

 

[5jj]

Source: Kangxuan

Who is Kangxuan?

 

[sitifan]

Who is Kangxuan?

Kangxuan is a publisher of textbooks in Taiwan. I don't know who wrote the sentence.

 

[Tarheel]

Nowadays, not only do people in Ireland celebrate it, but also people in many countries around the world celebrate this day to enjoy Irish culture. (My bold.)
Source: Kangxuan Educational Publishing Group.

Can I rewrite the quoted sentence as follows?
Nowadays, not only do people in Ireland celebrate it, (but) people in many countries around the world also celebrate this day to enjoy Irish culture.

It's OK, but I prefer the original. As for Irish culture, I'm not sure what bar-hopping has to do with that.

 

[sitifan]

Nowadays, not only do people in Ireland celebrate it, but also people in many countries around the world celebrate this day to enjoy Irish culture. (My bold.)
Source: Kangxuan Educational Publishing Group.

Is the word "do" obligatory, optional or redundant?

 

[Tarheel]

Is the word "do" obligatory, optional or redundant?

I don't know how you could could possibly "do" without it.

 

[emsr2d2]

Nowadays, not only do people in Ireland celebrate it, but also people in many countries around the world celebrate this day to enjoy Irish culture. (My bold.)
Source: Kangxuan

Can I rewrite the quoted sentence as follows?
Nowadays, not only do people in Ireland celebrate it, (but) people in many countries around the world also celebrate this day to enjoy Irish culture.

The whole thing is very confusing unless you explain that you're talking about St Patrick's Day.
I don't like "enjoy Irish culture". They're not enjoying it, they're celebrating it. That's why it's called a celebration.
I wouldn't open with "not only do people". I'd start with "XXX is not only celebrated/XXX is celebrated not only/just ...".
To sum up, here's what I would say:

St Patrick's Day is celebrated not just in Ireland; people all over the world now spend the day celebrating Irish culture.

 

[emsr2d2]

Source: Kangxuan

Kangxuan is a publisher of textbooks in Taiwan. I don't know who wrote the sentence.

In that case, that's not sufficient information for a source. You should know by now that we need the title of the book and the name(s) of the author(s). The name of a publishing company is never enough.

 

[sitifan]

In that case, that's not sufficient information for a source. You should know by now that we need the title of the book and the name(s) of the author(s). The name of a publishing company is never enough.

It's not quoted from a book. It's quoted from a handout of three pages, published by Kangxuan Educational Publishing Group. Kangxuan's salesperson gave the handouts to teachers for free.

 

[emsr2d2]

It's not quoted from a book. It's quoted from a handout of three pages, published by Kangxuan Educational Publishing Group. Kangxuan's salesperson gave the handouts to teachers for free.

OK. Perhaps the next time you see that salesperson, you could point out to them that you sometimes quote the material externally so you need to be able to provide the full source. Hopefully, they'll be able to tell you all the information you need.