First step to diagnose this is to determine if the webparts are there and showing, but just not visible due to some styling.
Please follow the below steps and tell me what you find:
- When you view the source of the page, do you see the HTML generated by the webpart? If you do, then it's actually there and it's a styling issue. If not, it's not rendering
- Is the RTL languages using the same template? You can define a differnet template for other language cultures, check to make sure it's not switching to a template that doesn't have it.
- Is the webpart actually there in the template? Check the Page Template module and look at the "WebParts" tab of it and scan the XML and see if you see the webpart in there. If your site has a "Default Style Sheet" defined in the Site module, you can try removing this so no style sheets are rendered through the Page Template module (which can block seeing web parts). If the webpart does not exist in the WebPart's tab, then it needs to be added.
- If the webpart IS there, then check any "Visible" setting on it, see if there is some logic that would cause it to be invisible on the RTL languages.
- Lastly, if the web part is there, nothing should be making it invisibile, you may need to debug the web part and step through it and see what's going on.
Hope those steps help, tell me what you find!