'Date Taken' metadata Pandora's Box & Lightroom

I scan slides and negs. I need to correct 'Date taken' on them afterwards (from the 'scanned date').
When I do it in picture editing programs (Lightroom, Photoshop, ACDSee, even in Widows Explorer) DOpus and all the other programs see it, and read it correctly.
When I make a change in DOpus ('Date Taken'), only Opus and Windows Explorer will recognize it, other programs will display all sorts of other dates instead.
I know there are 3 competing standards (EXIF, IPTC, XMP) creating lots of confusion, but couldn't Opus satisfy them all by populating relevant metadata fields 'behind the scenes'? I love Opus, but it doesn't do one thing I need most as a photographer - to be able to change dates before importing to Lighroom. [Other matadata work fine: e.g. 'Title' and 'Description'). Any ideas? (Script/button would be fine too).

Already replied to duplicate comment here: Change photo creation date/time for Lightroom

I've de-listed this thread so that people don't find the wrong one that doesn't have a conversation in it.