I have taken up this project of transliterating Geeta shlokas in Devanagari. I have set the project up here. I want to seek community help in transliteration work. However, I do not know what is the right platform to post this. Can you please guide me where can I post this. If this question is inappropriate for meta stackexchange, please let me know and I will remove it.
I don't think any site within the Stack Exchange Network is open for such requests.
The communities here exist to ask and answer questions, nothing more nothing less. The sites are not a job board or free advertising platform.
Your only option in the link to your project in your user profile and post questions about issues you run into while transliterating, In such posts you could mention your project but it is frowned upon if you direct link to it.
If it's not too much indirection, you might be able to ask on Community Building how to build a community of volunteer translators. While the answers you get there are unlikely to include what SE site to post on, I expect they will still have value in solving your underlying problem.
As well, if there is an SE site that naturally attracts people who might want to help you, consider putting a request for volunteers (and a link) in your profile on that site, and being an active participant there. That is a slow-and-steady way to attract people that might build up mass over time.