Getting data from main project html page?

I'm not sure I fully understand what you try to achieve.

I understand that you want to post date of a form to a sparkle server and currently you do this directly from a HTML page but somehow want to integrate this with a TMS WEB Core application.
If this is the case, the more logical choice imho would be to perform the form post directly from a web core page. You can use the TWebHTTPRequest for this. Have you considered this?