* I regularly get letters addressed to my first name and my middle name, missing my surname.
* Banks and airlines always seem to try a different way of dealing my middle name, from only using an initial to abbreviating it to anywhere from three to six characters.
* A friend once got issued travel documents where all of their given names were concatenated together (no spaces) and printed after their last name.
* Many websites still require you to pick an honourific from a drop down menu, but the options vary considerably (and usage is different in every country, even with a common language). Just make it a text field and be done with it.
I really don’t think it’s too difficult nowadays, especially if you’re writing something from scratch, to just accept really long Unicode strings and store given names and surnames separately. And it’s not like testing this is difficult - you can find datasets of a few hundred names in different languages and scripts fairly easily.