It's weird. KDE5 should auto update the menu anytime new software installed. Check /usr/local/share/applications if a SeaMonkey.desktop file exists.FreeBSD 12.0 KDE5
After installing programs such as seamonkey (# pkg ins seamonkey), I am unable to find it in any menu. I must hit (alt + f2) and type ‘seamonkey’ in the field and hit ‘enter’ to launch the program.
How can I put the installed programs into the system menu?
If you do not have desktop start try to make a shortcut by an icon for those programs.