Anti-Aliasing Custom Font in Digital Watchface?

Hello, everybody,
I am new here the developer of the Watchface "Ambi"

https://apps.garmin.com/de-DE/apps/bf70dbb4-905a-4430-bb49-87dbe6f50c09

Please forgive me, but this is my first Watchface and I am not a super developer.

After reading a lot here in the forum and on other sites, I still haven't found a solution.

I created the numbers 0 - 9 in a PNG file (relatively high resolution) and a FNT file.

The time is drawn as with drawText into the Watchface.
But now the edges of the numbers are not very smooth.
According to the documentation drawText does not support "antialiasing".

I'm desperate, how do I make the numbers appear smoother?

Thank you guys for your support.