Imposible to set :weight Light for a font

[Ypo]

Hi

Another noob X file:

I can't set ":weight Light" for a font.

If I set it using the "Menu, Options, Set Default font, Cascadia Mono - style Light"; the text in the buffer changes correctly;

https://i.postimg.cc/htZ4rL2w/1.jpg

but in the init.el the :family changes into "Cascadia Mono Light".

https://i.postimg.cc/VL3Dbp8H/2.jpg

When restarting, it seems that family "Cascadia Mono Light" doesn't exist, so the default font family changes by itself into "Frank Ruhl Hofshi".

In the customization buffer family is "Frank Ruhl Hofshi",

https://i.postimg.cc/y8Kg3yDz/3.jpg

but in the init.el family is "Cascadia Mono Light".

https://i.postimg.cc/XqFqpr3J/4.jpg

If I set in the customization buffer (:family Cascadia Mono :weight light) the default font in the buffers doesn't acquire the :weight light.

In the init.el it appears :family "Cascadia Mono" :weight light.

In the customization buffer weight goes back to "normal".

https://i.postimg.cc/QxmsSQ6D/5.jpg

Could it be related with light and Light capitalization?

Could it be some kind of curse for using a non free font?