I don't know if it's in plugin or core, it's for transaltion file.
I start to translate in french and in french there are some apostrophe/quote and non-breaking space.
When i make some translation, i like to use utf8 encoding (' for ' and   for nbs )
But actually & is replaced by & ( url encoding issue ?). If it's needed maybe do a utf8encoding bedore replace & is a good idea. If it's not needed, why use url encoding ?
For ', i can use \' ( don't like it's hard to read for me) but for nbsp i don't have a solution.
Thank's a lot