One of the examples for Devanagari that is claimed to be broken is a nonsensical combination that really isn't supposed to work either as per any of the Devanagari script using languages or the Unicode standard.

Devanagari (roughly speaking) has Consonants (with an inherent vowel A), dependent vowels signs added to a consonant, and independent vowel letters. And a few other signs for aspiration, nasalization, and cancelling the inherent vowel to combine consonants.

न्हृे Starts with N (the consonant NA with the inherent vowel A cancelled and ends with the Devanagari Consonant HA with _two_ vowel signs added to it - DEVANAGARI VOWEL SIGN VOCALIC R and DEVANAGARI VOWEL SIGN E

CV is the standard for Devanagari "syllables". When you do want to write two vowels after each other, you would write CV, and then another independent Vowel letter, so it would look like

न्हृए (which would end with DEVANAGARI LETTER E instead of DEVANAGARI VOWEL SIGN E)

*These are syllables as per the script definition rather than linguistic syllables.

https://www.unicode.org/versions/Unicode15.0.0/UnicodeStanda... section 12.1 has more details on the specifics of implementing Devanagari script, but not necessarily all of the conjunct forms between consonants, which are used especially when rendering Sanskrit.