Has anyone patched Thai UI fonts on firmware 5.x?

I’m using a Tolino Vision Color that has been switched into Kobo mode on the newer 5.x firmware branch (currently 5.12.232736).

Everything is working surprisingly well:

* Kobo UI works
* KEPUB works
* Thai fonts can be used inside books
* Reading Thai content is fine

But I still have one issue:
Thai book titles in the Kobo UI / My Books screen still show as □□□□ (square boxes).

Things I already tried:

* Installed Thai fonts (Prompt / Noto Sans Thai Looped) in `/fonts`
* Set Thai language metadata in Calibre
* Converted books to KEPUB
* Set Thai font as main reading font + supplemental font
* Renamed fonts to Avenir / RakutenSerif names
* Rebuilt font cache

The reader layer works fine, but the UI layer still doesn’t display Thai glyphs.

Has anyone successfully patched Thai UI fonts on firmware 5.x?
Or found the correct font path / font alias used by the UI layer?


Thanks!