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