MediaWiki:Size-kilobytes/qqq, MediaWiki:Size-megabytes/qqq, MediaWiki:Size-gigabytes/qqq

I agree that this is far from an ideal situation. It is very awkward to have a message say one thing but be used in a very different way by the core code. This could have been fixed really easily by changing the original English wording to match its actual use—but those messages go through a different vetting process which turns out to be slow as molasses in January at the North Pole. Meanwhile, the translations can effectively resolve the problem by making the messages 100% accurate. Eventually, the English messages will follow suit, or maybe the code will change differently and have two sets of messages (one using decimal prefixes, the other binary prefixes), at which point it should be trivial to update the translations.

Part of the problem is that there is faction of developers who are actively hostile to the disambiguation of the messages. This schism has been festering for at least 20 years now. A good example is the discussion that can be found here: https://bugzilla.mozilla.org/show_bug.cgi?id=106618