Why do keycodes for numbers work but keycodes for letters (like 'a', 'b', etc.) do not on Android TV?

Question

I'm working on a Remote project where I'm sending commands to an Android TV using a byte buffer Through TLS Connection. The command structure looks like this:

[6, 82, 4, 8, keycode, 16, 3]

For reference:

For volume control, sending keycode 24 (for volume up) works fine. I can also send keycodes for numbers, like 8 for 1, and those work perfectly in the input text area. However, when I try sending keycodes for letters, like 29 for a, 30 for b, and so on which is defined here, they don't seem to work at all.

I've confirmed that the byte array is sent correctly, and the Android TV is receiving the data, but it seems like the keycodes for letters are being ignored or not processed properly.

Has anyone encountered a similar issue? Is there something specific that I might be missing when sending keycodes for letters on Android TV?

Edit I am using protobuf for creating this command