i really don't like ए ऐ ओ औ for spelling vowel length. i don't think any natlang does this. please use ऎ ऒ if you don't wanna use the hindi convention.
also, i really like devanagari for conlanging. it's basically an alternitive to the ipa that actually looks good.
i would also suggest trying to keep the letters closer to how they're actually pronounced. /x/ and /ɣ/ on ह are likely to be confused with ख and ग because of nuqta orthography1. especially, /ʐ/ and /ɻ/ distinction if you're not using contrastive voicing and keeping /ʂ~ʐ/ as allophonic. fricitaves and approximates are very similar actually, and many languages confuse [ʐ] and [ɻ].
i think your readings of व and स are probably fine. i would suggest ditching the ipa notation and notating the allophony with other devanagari letters and/or linguistic description. also your phonology is very similar to indo-aryan langauges in general. maybe try removing or adding sounds, or maybe play with some things like marathi affricates or sindhi implosives.
in my opinion if you're making a language that uses devanagari and you need the ipa to explain how it works then you're doing it wrong.
1or use the nuqta letters to write them and use ह for hindi-style ऎ ऒ sounds. i don't know if this is a good idea or not.
I'm trying to avoid nuqtas and keep it as supported across as many fonts as possible; So those letters are out. The Kannada script (Among others) uses long o and long e in the parts usually used by the dipthongs. I do think I should move the allophones (And my conlang doesn't allow for vowel clusters, so I could prolly make the dipthongs allophonic)
I also want to keep it decently easy to speak by most people who speak at least one Indian language, while filling the box neatly and allowing me to take advantage of the cool ordering used for brahmi script using languages; This is a decently rough draft.
It's also fully compatible (In it's current state) with Malayalam, and no other languages. Malayalam is not an Indo-Aryan language-
I don't understand much, but I like the idea of using the script. It's so regular and neat. But for an outsider like me, it may be hard to follow if you post a lot of text without any transcription.
This forum does have collapsible elements,
so you can stash IPA transcriptions for the noobs
without detracting from the aesthetic of your language.
Btw, is there a reason that you listed the places of articulation in the order palatal, velar, retroflex, labial dental? Indic scripts are usually listed from velar to labial, right? Going from the back of the mouth, just as IPA goes from the front to the back.
Are you going to be using diacritics or for the vowels, or always standalone letters?
Are there going to be ways that the features of the loglang and the features of the script line up and make distinctions in the writing that correspond to grammatical or semantic distinctions rather than just phonetic ones?