See: https://github.com/bitcoin/bitcoin/blob/master/doc/translation_process.md
We generated the bitcoin_en.ts via:
<pre> python share/qt/extract_strings_qt.py lupdate bitcoin-qt.pro -no-obsolete -locations relative -ts src/qt/locale/bitcoin_en.ts </pre>
AFAIK this no longer works, as we don't have any working .pro file. We need a working translations process and as I'm no Python script guy, nor have any autotools knowledge, someone needs to look into this :). @laanwj @theuni Can you please take a look?