Hi,
I've had it a couple of times before in the past. KM would pop up with this window (see screenshot below) as it launches. It's probably more to do with the font than with KM. But I don't understand why it happens, and if this is some sort of necessary updates, and if unnecessary, is there anything I can do to prevent it from happening again?
I remember I saw it happen with another app before. But KM has it most frequently in the past.
Hey Martin,
Hm...
I just looked, and I don't have that font on my system – so it's not an operational requirement for Keyboard Maestro.
My best guess is that you have a macro that contains that font in styled text somewhere, but it's just a guess.
-Chris
The font is a simplified Chinese one @martin - do any of your macros process Chinese at all?
That is not a Keyboard Maestro alert - Keyboard Maestro does not include the text “needs to download” anywhere.
I'd guess its a system thing, and a quick search found this Microsoft page with 560 “I have the same question” comments:
It's a system setting, if you open Font Book, you'll see that you can download it. but as already mentioned, it's optional.
Thanks, @ccstone, @tiffle, and @peternlewis.
I do have Chinese in some of my macros. I'm familiar with this font, and I probably have used this font in some of the comment actions. But now, it's difficult to locate them. Is there a way to search a macro that uses this font?
I have the same guess.
I guess when this download needs to happen, launch any app that uses this font will trigger this download pop up. It happens to KM most often because I open the KM Editor almost every day. The one time that another app had this issue was probably because I happen to start that app first that day and that app also used this font. But I don't understand why this download pop up window exists. Is there an official place that allows uses to download fonts and pushes updates to users?
If it does not come with the MacOS system, it probably comes with another app, or I might have downloaded and installed it manually. Then It should not expect it to be handled at the system level, should I? 
I'm pretty sure I had the font downloaded already. And, every time I saw this pop up window, I chose the "Download" option. (I haven't tried "Skip". But I was thinking, if I skip, it might pop up again next time.) I never delete this font from the Font Book. So unless there is an update push, I don't understand why this "Download" is triggered...