Ayaka Ito

Does "....aaa aaa in English, ... and aaa aaa in French...." mean that the French is not translated?

No. aaa aaa is a proper name. The English source texts don't use a no-break space in the proper name but when translating it to French, a space was translated to a no-break space.

ok.  The first thing is your expression is generally incorrect because you are simply validating that the source has a normal space, and the target doesn't.  So you get a warning.

You need to be more specific and if you must use a back reference then something like this:

(aaa)(?:\x20|\xA0)(aaa)

$1\xA0$2

Grouped Search Expression - report if source matches but not target

I only added this part (?:\x20|\xA0) instead of just \x20 because you seemed to have used something in the source and I was guessing you tried to show a normal space and a non-breaking space... wasn't sure.

ok.  The first thing is your expression is generally incorrect because you are simply validating that the source has a normal space, and the target doesn't.  So you get a warning.

You need to be more specific and if you must use a back reference then something like this:

(aaa)(?:\x20|\xA0)(aaa)

$1\xA0$2

Grouped Search Expression - report if source matches but not target

I only added this part (?:\x20|\xA0) instead of just \x20 because you seemed to have used something in the source and I was guessing you tried to show a normal space and a non-breaking space... wasn't sure.

Dear Mr. Paul. Thank you so much for your help. I could finally found the correct regular expression pattern by your support.

Excellent... glad you managed to sort it out.