I think the worst example of this overzealous localization was when some person translated the VB(A) reserved keywords to the appropriate language (I want to say it was german or swedish). Happened in the 1990s.
Your programming language reserved keywords changing depending on your selected language was a big facepalm.
Searching for this problem on the web doesn't produce any valid relevant results, so the web has forgotten or maybe the horror has been plastered over.
VBA is still localized in many languages, I saw macros in italian.
It's not just VBA keywords either, even excel functions are localized. e.g. this is from microsoft's docs[0]
So obnoxious, although apparently in newer versions you can modify what language you want.
I remember seeing the dictionary to translate between German and English function names[1], one time I googled for "Excel German translation" and Google proudly showed the Translate interace pre-filled with "English: excel / German: übertreffen"
The feature itself isn't that crazy – it's even a good thing, especially considering that Excel (and to lesser degree, VBA) were designed for ordinary people and that in the 80s/90s English was less common than it is today.
Where it went wrong is that as soon as you choose a language you were stuck with that. It should have been a display option.
The missing part of that story is probably the file is a .xlsm (or even an older .xls with macros) and therefore has VBA scripts, which is not saved in a language-independent way.
Probably someone manipulating with formulas with VBA and improperly using FormulaLocal property. Formulas are stored in language neutral way and it shouldn't be a problem under normal circumstances.
Your programming language reserved keywords changing depending on your selected language was a big facepalm.
Searching for this problem on the web doesn't produce any valid relevant results, so the web has forgotten or maybe the horror has been plastered over.