Suggestion: How about make variants of the font(NotoSans)?
Use Light variant along to some Light font like PuristaLight, use Medium along to, use Bold along to so on.

Since NotoSans fonts are available from Google and have some variants, I assume this is not a hard work.

Another example.

And what exactly is the problem? The text is too small to read? In what situations? What UI settings do you have?

Actually, the problem is: In any UI settings or interface scale, the font weight of Asian fonts don't correspond to that of Latin fonts so that a text supposed to be bolded will be shown in Light as shown below and some texts are very thin to read especially subtitles after Apex as shown in the description. Sorry to make this confusion, that was a bad title.

hint parsetext "<t size='2'><t font='PuristaLight'>This is a text; </t><t font='PuristaBold'>This is a Bold Text</t><br/><t font='PuristaLight'>これは文章です; </t><t font='PuristaBold'>これは太字です</t>"

The ideal solution for me is to create other Asian fonts with different weights and apply to in-game fonts.
Like,

• NotoSansCJK-Light for EtelkaMonoSpacePro, EtelkaMonospaceProBold, PuristaLight, RobotoCondensedLight
• NotoSansCJK-Regular for EtelkaNarrowMediumPro, PuristaMedium, RobotoCondensed
• NotoSansCJK-Medium for RobotoCondensedBold
• NotoSansCJK-Bold for PuristaBold, RobotoCondensedBold

Please discuss this problem with UI designers and Asian localizers especially Rumi Tasaki(if possible).

Thanks for this. I am afraid there is nothing we can do about it right now, but I will keep it in the pipeline and see what we can do about it in the long run.