I'm not sure what your goal is...

"Hütte" has 5 unicode characters but no diphthongs:

use v5.12;
use warnings;
use utf8;     # treat source-code as utf8 including string-literals

my $t = "Hütte";

say length($t); # 5

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FWIW:
"ü" is not a diphthong but an umlaut. The transcription "ue" neither, because it's still just pronounced as one vowel not two.

Compare "au" (eg "Braun") which is a diphthong (di=two)

Umlauts are not alien to the English language, there are just no formalized characters for it.

Compare the switch from "foot" to "feet", or "mouse" to "mice"

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

Update

Restructuré

In reply to Re: incorrect length of strings with diphthongs by LanX
in thread incorrect length of strings with diphthongs by tos

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