[KevinH]

In case anyone wants to test this in their own current build of Sigil just to verify it does not mess anything up for them:

1. Make backup copies of all your sigil related ini files in your Sigil Preferences folder

You can use the Go To Sigil Preferences Location button or use your file explorer:

    For Example: on a Mac they can be found here:
        /Users/YOURUSERID/Library/Application Support/sigil-ebook/sigil
            sigil.ini
            sigil_index.ini
            sigil_clips.ini
            sigil_searches.ini

2. Make the following changes to Sigil/src/Misc/SettingsStore.cpp

--- src/Misc/SettingsStore.cpp~	2017-12-05 09:01:06.000000000 -0500
+++ src/Misc/SettingsStore.cpp	2018-10-23 10:59:11.000000000 -0400
@@ -100,11 +100,13 @@
 SettingsStore::SettingsStore()
     : QSettings(Utility::DefinePrefsDir() + "/sigil.ini", QSettings::IniFormat)
 {
+     setIniCodec("UTF-8");
 }
 
 SettingsStore::SettingsStore(QString filename)
     : QSettings(filename, QSettings::IniFormat)
 {
+     setIniCodec("UTF-8");
 }
 
 QString SettingsStore::uiLanguage()

Then rebuild and launch Sigil. Sigil should now safely convert all of your ini files to use utf-8 format.

Then test everything and report back if any clips, preferences, saved searches, etc cause you any issues.

Please note - this is a one-way change to your ini files to make them more readable and editable by humans. Once you are done testing, if you want to revert back to the official build and then you will need to put back your sigil related ini files from your backups **before** firing up the older version of Sigil.