Before:
Highlighted candidate uses theme.highlightColor for text, but this color should only be used in background color, not text color. This style is different from other KDE UI.
{F3870601}
After:
Highlighted candidate uses theme.highlightedTextColor for text, and theme.highlightColor for background.
{F3870602}
It is more similar to general KDE design:
{F3870614}
And more easier to read.