New Computer Modern "Book" and "BookItalic" variants not recognized by Illustrator (Windows)

I'm having trouble getting Adobe Illustrator to recognize specific variants of the New Computer Modern font family (OpenType/CFF, .otf format) on Windows 11.

What works: Illustrator correctly recognizes the Regular, Italic, Bold, and BoldItalic variants (e.g., NewComputerModern10-Regular, NewComputerModern10-Italic, etc.).

What doesn't work: The Book and BookItalic variants (e.g., NewComputerModern10-Book, NewComputerModern10-BookItalic) are completely absent from Illustrator's font list, even though Windows recognizes them normally.

What I've already tried:

• Reinstalling all fonts globally ("Install for all users"), ensuring they are in C:\Windows\Fonts
• Clearing the Windows font cache (stopping the FontCache service, deleting cache files, rebooting)
• Clearing Illustrator's own font cache (AdobeFnt_OSFonts.lst)
• Inspecting and editing the fonts' internal metadata with FontForge

Evidence from AdobeFnt_OSFonts.lst:

Inspecting Illustrator's font registry file confirmed the problem. For the NewComputerModern10 family, only these entries exist:

FontName:NewCM10-Bold
FontName:NewCM10-BoldItalic
FontName:NewCM10-Italic
FontName:NewCM10-Regular

NewCM10-Book and NewCM10-BookItalic are simply not there — Illustrator never registered them.

Additionally, I noticed inconsistent entries elsewhere in the same file, where two blocks share the same FontName but different WinName values:

%BeginFont
FontName:NewCMSans10-Book
...
WinName:NewCMSans10-Book
%EndFont

%BeginFont
FontName:NewCMSans10-Book
...
WinName:NewCMSans10-Regular   ← same FontName, different WinName
%EndFont

This suggests the .otf files themselves may have inconsistent internal metadata, which could be causing Illustrator to silently discard certain variants.

Additional evidence: font metadata is correct

I also inspected and edited the internal metadata of the affected fonts using FontForge. Both NewCM10-Book and NewCM10-BookItalic have well-formed TTF Name entries:

• Family: NewComputerModern10
• SubFamily: Book / BookItalic
• Preferred Family: NewComputerModern10
• Preferred Styles: Book / BookItalic

Even after editing and reinstalling the fonts, Illustrator's behavior did not change. This suggests the issue lies within Illustrator's font registration logic, not in the font files themselves.
 

My hypothesis: Illustrator conflicts when both a "Book" variant (WeightClass 400, StyleBits 0) and a "Regular" variant (identical values) coexist within the same font family, causing one to be silently dropped. Is this a known limitation? Is there a workaround short of renaming the fonts?