I think it might be less of a language difference and more related to the text alignment.

Try the macro on text that is left aligned vs fully justified vs right aligned. Do you get consistent results for one alignment vs another alignment? On my Australian English text doc, I get a better result on Left Aligned text but not with other alignments. For some reason, centred text circles are wider than left aligned text of the same size.

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Andrew Lockton
Chrysalis Design, Melbourne Australia