This post is from 2015, and I'd love to know if unicode has added better support for non-English languages since then.
https://modelviewculture.com/pieces/i-can-text-you-a-pile-of...
Based on https://en.wikipedia.org/wiki/Bengali_(Unicode_block), only 3 more Bengali characters have been added since 2015.
I am not a Bengali-speaker, but I am familiar with the class of scripts to which the Bengali script belongs, abugidas. These scripts assume a vowel following every consonant. When two consonants occur one after the other in a word (a consonant cluster), this must be represented specially, because if you just wrote (consonant, consonant) it would be pronounced (consonant, inherent vowel, consonant).
The "ty" in Aditya is one such consonant cluster. The way this cluster is written is ত্য. This is represented as three code points (I think I am messing up the proper terms), one for the "t", one to "join", and one for "y".
Some people think of the special shape that the final "y" as a separate character on its own. In fact, it has it's own name (ya-phalā). I can understand why it would be confusing to see that the ya-phalā can't be typed as its own single character (" ্য"), but it really has to do with a difference in how the input is is implemented and how the person thinks about their own language.
In fact, on the unicode.org site, typing this very character is part of the FAQ for Bengali: https://unicode.org/faq/bengali.html#6
It's complicated, but the author of the piece seems to take issue with how the character set was designed by the language authorities the UTC delegated to.
The whole comment thread is an interesting read.
Tell us that story please!