Cearbhall,

A couple more general observations:

1.  Although LibreOffice is accessible, by and large, it is not as "nicely accessible" as Microsoft Office is.

2.  Microsoft Office, being the de facto standard Office suite of the world (and anyone who wants to argue that with me, don't bother, I've been in the private and public sector in the USA and paying attention to users overseas in these very forums - Microsoft Office vastly predominates) the various screen reader developers focus on compatibility with it, first, for very good reason.  When you've got limited resources, you focus where they have the most impact.

3.  Screen readers are directly dependent on what the software they're working with exposes to them for auditory presentation.  It doesn't matter if it's an XLSX file if LibreOffice does not expose certain elements of the file structure to NVDA (or JAWS, or whatever screen reader) for presentation to the user.  There's a lot of "handshaking" type information exchange, and if one hand is not extended, the other can't grab it.

My guess is that it's item number three in my above observations that accounts for the difference in what NVDA is able to present when using precisely the same file in MS-Excel versus LibreOffice.  It likely lies in what Excel versus LibreOffice exposes to NVDA.
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Brian - Windows 10, 64-Bit, Version 21H1, Build 19043  

The ignorance of one voter in a democracy impairs the security of all.

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