I still remember with dread working on a Word Basic "application" to generate MS Help documents for an internation company's ISO 9001 quality manual back when it was still Word Basic. One challenge was that the Norwegian subsidiary had "inherited" this code from the Danish subsidiary. And Word Basic was localized.

The problem is, some of the code had been cut and pasted and saved as text and Danish and Norwegian are very close so sometimes that would work, and sometimes it would seem to work but errors would lurk around every corner, and only occasionally would it fall flat on its face in obvious ways (if it'd been transferred from a different language version at least it'd been more likely to be obvious on reading through the code what needed to be modified..)

I am of an opinion that it should be an option for people who really want it, but it should not be an acceptable industry practice to write code/comments in a language other than English. Latest example of this is the official Sony PSM SDK, which has half of its documentation and code comments in Japanese. So now Sony has to pay somebody to actually translate it, instead of simply insisting on their Japanese programmers using English in the first place, which I am pretty sure they are perfectly capable of. The same situation with the official PS3 SDK - but that was released more than 7 years ago now,so I doubt that they will ever fix it. And that's a product for which you have to pay serious money as well, so it's completely unacceptable.