You may want to PM
Raja1205, since he seems to have figured out how to create valid Tamil epubs.
Here are some general hints:
- By definition, epubs need to contain Unicode files only. I.e. TSCII source files and TSCII fonts cannot be used.
- Calibre might not be a good choice for converting .html files to epubs. It's better to generate the epub in Sigil.
- Make sure to set the correct language code in the Metadata dialog box.
- You'll need to embed a Tamil Unicode font for pretty much all epub readers, except for iPads.
- Font embedding can be tricky. Even if the epub looks OK in Sigil, it doesn't mean that font was correctly embedded. Make sure to click the green checkmark button to check the epub for errors. This should also identify any link errors.
- AFAIK, Latha is a Microsoft Tamil Unicode font that you cannot legally embed in epubs that you intend to distribute, because Latha was licensed for Windows only. Try to find a similar Open Source Unicode font.