There have been quite a few new LBook Firmwares posted in this thread:
https://www.mobileread.com/forums/showthread.php?t=80822
For those who like to experiment with them, I guess the major hassle is to have to customize all the settings of CoolReader each time you upgrade to a new version: hyphenation, font spacing, margins, button functions, etc. I've found in the-ebook-org a very practical solution.
Download the following ini files:
crengine.zip
Unzip and put all the ini files into the Root/crengine folder (it should be there already). Don't change their names or they won't work. Open an ebook in any format (let's say a fb2 book). CoolReader will be working now with all my settings (Note: short press on menu button for menu settings). Now customize it the way you prefer (hyphenation, font spacing, margins, button functions, etc.), and all your settings will be saved to the corresponding ini file (in this case the 'cr3-fb2.ini'). Connect your reader to your PC. Open the cr3-fb2.ini file, select all, copy. Then open the other ini files and substitute their contents with the one of the cr3-fb2.ini file. This way you can keep all your settings, no matter how many times you change or upgrade your firmware. To be safe, make a backup copy of all the ini files in your computer.
You can also keep a different set of settings for each ebook format. There are many interesting settings to explore in the ini files, even the background color.
Hope it helps. If you have any trouble, just erase the ini files from the crengine folder.