If you use gettext, the site can easily switches from one language to another and there are good programs which allow you to match your translation with changed strings in future versions, so you can update it without search what's changed.
Have a look at the wikipedia page for gettext: https://en.wikipedia.org/wiki/Gettext. The system features things like plural forms, fuzzy matching, single line vs. block translations and much more. And there are a lot of programs to make it easier to deal with the files. I like to use gtranslate, but from the screenshots Poedit looks nice as well.
If you really want to, go on and translate the raw text. This can still be converted to gettext files and I do not want to stop you from helping. If you want to do so, put your translated files in another folder, so I can merge them without overwriting the original files.