Some additional repos to consider:
geekwright/Po — Objects to assist in reading, manipulating and creating GNU gettext style PO files.
potomoco — PHP gettext compiler (.po to .mo)
circlical-po-editor — Gettext *.PO file editor and parser for PHP. Also scans code to find translatable text.
Once a week...... I send out a list of most interesting PHP libraries and apps.
Want to get it?