Unfortunately the C++ name mangling in a 64-bit MSVC compilation is
slightly different from that in a 32-bit one:

-- An 'E' is inserted for pointers to indicate that they are 64
bits. I don't fully understand the rationale for this; isn't that the
only kind of pointer in 64-bit code produced by a C++ compiler anyway?

-- As there is only one calling convention on x64 Windows, __cdecl,
the indications for other calling conventions (here, especially
__thiscall) change to that for __cdecl.

It should be possible to write a tool to at least partially automate
conversion of 32-bit mangled names to 64-bit ones, and thus make it
easy to create mscx map files from the corresponding msci ones in
LibreOffice. Sure, it probably wouldn't work 100% correctly in all
cases, but it would help a lot.