Following discussion in bug #65671 I have changed the Bug report to an Enhancement request. Please consider changing Formula arguments to English when Formulas are *deliberately* set to English by the user. Repeating what is argued in bug report #65671 "If a user selects the "Use English function names" (under Tools> Options> LibreOffice Calc> Formula) then it is because he/she is used to typing formulas in English. In this situation it doesn't make sense that valid arguments are expected in the language defined in Locale Settings." I add to this that Outputs should also be in English. It doesn't make sense that every calculation is in English and then the output is in the local language (e.g. #NOME instead of #NAME or FALSO instead of FALSE)
thanks for reporting :)
Meanwhile short error names like #NOME? vs #NAME? are part of the function name language. FALSO vs FALSE and other automatic number formats and recognition of inline numeric arguments depend on the default locale, you can switch that to some English locale as well under Tools -> Options -> Language Settings -> Languages, Formats, Locale setting. Coupling that with the switch to/from English function names IMHO is not a good idea. Having different separators/formats for numeric being accepted depending on whether it's a cell input or a formula input is even more confusing. I tend to close this as WONTFIX.
For inline mere numeric arguments this makes sense and now thy are "English" (using the '.' dot decimal separator) as well since commit 0a78f11fdd13d914d5f063007b2df9796e6dce9d for bug 135993 that takes the symbol map's bEnglish setting.
Reopening because that new behaviour has been reverted for bug 151886.