Very often you have to make a simple presentation website that doesn't need a complex CMS at all - a simple HTML file with some JavaScript would be fully sufficient.
However, it is still very useful to have an internationalization support. And then you have to use some actual framework or CMS; but this is so pointless because all you really need is just a translation support.
Please note that this is not a duplicate of questions such as this, because I could, of course, define a simple PHP file with translation array. But often you don't need to do this by yourself, but have a third person do it, so you need some simple administration area where you could edit the strings in a browser.
So please, does anyone know of a simple, file-based (ideally single file+internationalization files) PHP library with a simple login-restricted area where you can edit the strings in a browser?
I would definitely not like to reinvent the wheel :(
Note: this is a repost of this question, as it seems that that it's not ok to ask for recommendations on Stack Overflow anymore