On KDE System Setting's Font page, you can change fonts by using the "edit" buttons on the right. However, the tooltips (cursor hovering popup message) of those buttons have unneeded colons (:) after their name type.

For example, for General, the tooltip becomes:
"Select General: Font..."
But it really should be:
"Select General Font..."

I took a look at kcm_fonts.pot, the tooltip code's location is:
package/contents/ui/FontWidget.qml:65

I guess the tooltip is using the Type strings on the left directly, which all ended with a colon. I could not find any other type strings in kcm_fonts.pot.