See https://wiki.apertium.org/wiki/Apertium_Simpleton_UI
This tool is designed for Windows and macOS. It may work on Linux, but no real effort has been made to do it correctly.
wget https://apertium.projectjj.com/apt/install-nightly.sh -O - | sudo bash
sudo apt-get install apertium-simpleton
sudo apt-get install --no-install-recommends build-essential qt5-default qt5-qmake qtbase5-dev git
git clone https://github.com/apertium/apertium-simpleton
cd apertium-simpleton
qmake
make -j4
sudo make install
If you do build from source, you will need all the Apertium core tools either also from source or from the nightly repos:
wget https://apertium.projectjj.com/apt/install-nightly.sh -O - | sudo bash
sudo apt-get install binutils apertium apertium-anaphora apertium-lex-tools apertium-recursive apertium-separable cg3 hfst lttoolbox