After downloading the font, you must tell your computer to accept Tamil 99 keystrokes.

This is the most common point of confusion. When you search for "Tamil 99 Font," you are actually looking for two different things:

It follows a natural phonetic flow, making it simpler than older typewriter-based systems. Top Free Tamil 99 Fonts for Download Microsoft introduces Tamil 99 keyboard on Windows 10

While you may already have Latha installed with Windows, many older versions lacked full Tamil 99 support. The updated version is fully compliant.