In the past I got permission to copy content from a resource with the names of languages. I am still grateful for the data. It got the Dutch Wiktionary going really nicely and, as we needed at the time those names of languages for the user interface.
With OmegaWiki we had the same issue; we needed language names again for the user interface. This was to make it possible for people to see the labels of translations in their own language. From the moment the data became available we have learned a lot, for instance that language in languages like Danish and Italian do not capitalise the names of languages.
Today I was told that many of the names of languages in Georgian were found to be in error and had been corrected. The great news for OmegaWiki is, that we only have to do this once and it is good everywhere. The sad thing is that it is probably wrong in many, many Wiktionaries. There were two types of errors; it was just wrong or it was the name of someone from a country in stead of the name of the language.
The best I can do for the Wiktionaries is notify in this way as I do not really now what needs doing.