Just a short note that I've discovered the switch in the Table of
Authorities field to retain original formatting does not work if that
formatting is applied using a character style. It does work if the
formatting is applied using direct formatting.

Once the TA field is generated, it is the formatting contained in the
field's long citation that is used, not that in the original entry. But if
that formatting is applied using a character style, it is disregarded. (I
use emphasis style often rather than Italics; I also use a custom citation
style which contains both Italics and "no proofing" settings. They need to
be replaced in the field with direct Italic formatting.

Not asking for solutions, the work-around works fine. Just passing on
another arcane tidbit.