Language Translation
First of all, prepare a development environment in your computer following the instructions here.
Download and install poedit. This app will help you to translate the strings and generate the required files.
Determine your language and region tags. For example, for Spanish/Argentina the tags are: "es" and "AR". With this info, create a new folder in pygubudesigner/locale directory:
mkdir -p pygubudesigner/locale/es_AR/LC_MESSAGES
Open poedit. Navigate to "File > New from POT". Select the file pygubudesigner/locale/pygubu.pot as the template. Poedit will ask for the target language, in this example Spanish/Argentina.
Start translating the strings to your language. Then save the file in the folder created before (pygubudesigner/locale/es_AR/LC_MESSAGES) with the name pygubu.po (this will also generate a pygubu.mo in the same directory)
To test the translation just start pygubudesigner in the development environment.
python -m pygubudesigner
If you do not see the strings translated, try to configure the LANG environment variable:
# for example in GNU/Linux run:
LANG=es_AR; python -m pygubudesigner
Finally, create a pull request with the new pygubu.po generated.