falkon - removing po/ files is sometimes needed.
On a 9.0-ish system where Qt had previously been using the "stable" 5.12 series I have just upgraded to qt-5.14.1. Obviously I needed to recompile the packages using Qt after removing /opt/qt.
Falkon failed in cmake because it couldn't find the KF5I18N cmake file. That is needed for the po/ files. Looking at #12937 I removed that in r22509 as part of the upgrade - that was on a fresh system, not sure why that one didn't need it.