I have no practical knowledge of Telugu but I had a look at the related Unicode section, both on my computer and on the site.
From what I understand from the writing system, consonants are primary units and vowels modify the shape of consonants as “diacritics”. In the chart (U+0C00 to U+0C7F), vowels have names like TELEGU VOWEL SIGN xx and the code points have property “combining character”.
The character you reference in your question, U+0C30 TELEGU LETTER RA, is a consonant and, ipso facto, has no combining property. The examples shown look like U+0C24 TELEGU LETTER TA and U+0C36 TELEGU LETTER SHA both with subscripted crescent. The form taken by the combination seems to be qualified as a “conjunct”. In other scripts, this would be named a ligature.
Ligatures are not handled manually by the author but automatically substituted when met. Ligatures are advertised through a table in the font file. The document processor uses the table to detect the combinations and access the composite character.
If this does not work for conjuncts other than SHA/TA + RA, this means the ligature has not been included in the font. As there is no combining character shaped as a subjoined crescent, you have no manual workaround.
Your only solution is to look for a font shipping with an extensive set of ligatures.
To show the community your question has been answered, click the ✓ next to the correct answer, and “upvote” by clicking on the ^ arrow of any helpful answers. These are the mechanisms for communicating the quality of the Q&A on this site. Thanks!
