Earlier when the font was created, the font appeared in Font Thumbnail shows in Telugu (అబక). After recent updates the font Thumbnail appears in English (Abg) instead of Telugu. Do I need to do any settings to show Thumbnail in Telugu ?
You might need to include Telugu in the Unicode Character Ranges.
I have looked into your specific issue, and the Unicode Character Ranges contain both Devanagari and Telugu. I think that combination causes Windows to just skip both as an option, and default back to Abg.
It works as you want as soon as you drop Devanagari from the Unicode Character Ranges. The font only contains one such character, so it probably isn’t a big deal.
I’ve recently become aware that Windows now prefers Design and Supported Languages to determine which sample set to display.
That might be something to look at too.