I developed a similar application using PyQt4 and Qt4-designer. You have to install pyqt4 all modules:
sudo apt-get install qt4-default qt4-designer qt4-doc qt4-dev-tools python-qt4
So in your case just change all 4-5 i.e qt4 -- qt5.
Well, I tried that and got the following:
E: Unable to locate package qt5-designer E: Unable to locate package qt5-dev-tools E: Unable to locate package python-qt5
So I assume it would be safer to proceed with pyqt 4 rather than pyqt5?