Hi Krishna,
I faced the same issue recently, but lately I realized that if you go to the jcr:content node of any of the rendition and checkout the property jcr:data of type Binary, you will see a View link in its value, you can click on that to download the rendition. Once you have downloaded copy of the asset rendition you may open it with notepad/gedit and then find(Cntrl+F) the metadata property or the value that you wanted to propagate to the rendition.
If you are able to find it, it clearly indicates that the metadata changes you made have perfectly propagated to the rendition.
Thankyou !