[JSWolf]

Originally Posted by droopy

Based on what I've read about the Lexend font, In the Lexend family, six out of the seven have wide spaces between the characters. I chose the one that looks like regular spacing. It's called Lexend Deca. I'd like to read all my books with that font, or at least be given the option to switch from the Publisher Default to Lexend. But there's one book where, even after switching from Publisher's Default to the installed Lexend Deca.
On my Kobo Forma, the book is in Kobo Epub format (filename ends in "kepub.epub").

When I change the font in other kepub books on my Forma, I do see the change. But not for this book. I don't know why. I enabled what I thought were all relevant patches.

Spoiler:

kobopatch_4.18.13737/kobopatch.sh
kobopatch cfae583
https://github.com/geek1011/kobopatch

Loading configuration from kobopatch.yaml
Reading input firmware zip

Patching ./usr/local/Kobo/libnickel.so.1.0.0
SKIP `Allow USB storage even when device locked`
SKIP `Allow rotation on all devices`
SKIP `Allow searches on Extra dictionaries`
APPLY `Allow showing info panel on random screensaver`
APPLY `Always show confirmation dialog before upgrading`
SKIP `Block WiFi firmware upgrade`
SKIP `Both page turn buttons go next`
SKIP `Both page turn sides go next`
SKIP `Change Browse Kobo home screen link target - Activity`
SKIP `Change Browse Kobo home screen link target - Articles`
SKIP `Change Wikipedia search language`
SKIP `Change dicthtml strings to micthtml`
APPLY `Custom Sleep/Power-off timeouts`
APPLY `Custom font sizes`
SKIP `Custom header/footer page number text`
APPLY `Custom kepub default margins`
APPLY `Custom left & right margins`
SKIP `Custom navigation menu page number text`
SKIP `Customize ComfortLight settings`
SKIP `Cyrillic Keyboard (GloHD/ClaraHD/AuraOne/H2O2)`
APPLY `DeveloperSettings - AutoUsbGadget`
SKIP `Dictionary text font-family/font-size/line-height`
APPLY `Disable all tutorial dialogs`
SKIP `Don't grab exclusive access to event0`
SKIP `Don't uppercase header/footer text`
APPLY `Don't uppercase header/footer text and change page number text`
APPLY `FeatureSettings - BookSpecificStats`
APPLY `FeatureSettings - ExportHighlights`
SKIP `FeatureSettings - FullScreenBrowser`
APPLY `FeatureSettings - MyWords`
SKIP `FeatureSettings - ShowFacebookShare`
APPLY `Force user font-family in ePubs (Part 1 of 2)`
SKIP `Force user line spacing in KePubs`
SKIP `Force user line spacing in ePubs (part 1 of 2)`
APPLY `Freedom to advanced fonts control`
SKIP `Greek Keyboard (GloHD/ClaraHD/AuraOne/H2O2)`
SKIP `Hide browser from beta features`
SKIP `Hide top-left menu item - Activity`
APPLY `Hide top-left menu item - Dropbox`
SKIP `Hide top-left menu item - Pocket`
APPLY `Hide top-left menu item - Recommended`
APPLY `Hide top-left menu item - Store`
APPLY `Hide top-left menu item - Wishlist`
SKIP `Ignore .otf fonts`
SKIP `Increase TOC level indentation`
APPLY `Increase TOC level indentation and fix extra indentation bug`
SKIP `KePub constant font sharpness`
APPLY `KePub stylesheet additions`
SKIP `Larger Sleep/Power-off timeouts`
SKIP `My 10 line spacing values`
SKIP `My 24 line spacing values`
APPLY `Never show Kobo Plus, wishlist, and points SmartLinks`
SKIP `Only show Pocket SmartLink`
SKIP `Only show stats SmartLink`
APPLY `PowerSettings - UnlockEnabled`
SKIP `Remove beta features not supported text`
APPLY `Remove recommendations (row1col2) from home screen`
APPLY `Remove title from reading header/footer`
SKIP `Rename new home screen footer`
APPLY `Replace adobe page numbers toggle with invert screen`
SKIP `Set KePub hyphenation`
SKIP `Set font scale factor`
SKIP `Set visible SmartLink`
APPLY `Shorten dictionary entry not found message`
SKIP `Swap reading header/footer`
APPLY `Un-Force user font-family in KePubs`
SKIP `Un-Force user text-align in div,p tags in KePubs`
SKIP `Un-force font-family override p tags (std epubs)`
APPLY `Un-force link decoration in KePubs`
SKIP `ePub constant font sharpness`
APPLY `ePub disable built-in body padding-bottom`
SKIP `ePub fixed top/bottom margins`
SKIP `ePub uniform font scale`

Patching ./usr/local/Kobo/nickel
SKIP `Change pop-up footnote font-family`
APPLY `Custom collection/author header title font`
SKIP `Custom new header/footer font`
SKIP `Custom page navigation scrubber`
APPLY `Custom synopsis details line spacing`
APPLY `Custom synopsis font size`
APPLY `Dictionary pop-up - increase available text area`
APPLY `Increase Book Details synopsis area`
APPLY `Increase headlines font`
SKIP `Increase home screen cover size`
APPLY `Increase library cover size`
SKIP `Increase size of kepub chapter progress chart`
APPLY `New home screen subtitle custom font`
APPLY `Reduce new header/footer height`
APPLY `Reduce top/bottom page spacer`
APPLY `Remove footer (row3) and increase cover size on new home screen`
APPLY `Remove footer (row3) on new home screen`
APPLY `Remove forgot pin button from lock screen`
SKIP `Show all games`

Patching ./usr/local/Kobo/libadobe.so
APPLY `Keep PDF pan position`
APPLY `Remove PDF map widget shown during panning`
APPLY `Remove PDF page turn arrows`

Patching ./usr/local/Kobo/librmsdk.so.1.0.0
SKIP `Default ePub monospace font (Courier)`
APPLY `Default ePub sans-serif font (Lexend Deca)`
SKIP `Default ePub serif font (Amasis)`
SKIP `Default ePub symbol font (Symbol)`
SKIP `Disable orphans/widows avoidance`
APPLY `Force user font-family in ePubs (Part 2 of 2)`
SKIP `Force user line spacing in ePubs (Part 2 of 2)`
SKIP `Ignore ePub TOC navpoints`
SKIP `Ignore ePub book Adobe XPGT stylesheet (page-template.xpgt)`
SKIP `Ignore ePub book CSS and Adobe XPGT stylesheets`

Still, the book is stuck to its own font, even if I try to manually switch the font in the book.

I noticed that changing font size in the settings does correspond to a change to the book's font size. Same with Line Spacing or Margins or Justification.

Do you realize that the Laxend font has no bold, italic, and bold italic versions? I don't know what will happen. You might see the regular version in place of bold/italic/bolditalic or you might see nothing at all. It's really a bad idea to use a font like this because it's incomplete.