Core metadata about images

I am trying to catalogue my photo collection (going back to the 40s and 
50s). Many are from scans of CTs or prints. I want to get input from 
sisters and family to add details which I don't know about the photos. 
They will not be using Digkam. I don't want to put the photos in the 
Cloud (too many).

I want to add the following information to each image:
caption
title (optionally)
date taken
place in image
people in image
optionally keywords uncontrolled (e.g. flowers, cars, lunch, cycles etc)

I want to send this info to them so that they can add or correct 
information. I thought the best way would be as a spreadsheet, pdf or 
html/xml file. Too big to print but they will have software such as 
Excel, Word etc.

It is hard to do this in Digikam. Best thing I have found is the table 
layout. Close, but I cannot output it to a file. And I cannot specify 
the fields to print/export. Same with HTMLGallery - Details but I cannot 
see how to easily customise it.

A bigger problem is the way the data is stored in the metadata. I can 
use Exiftool or a Python script to extract specific fields but I cannot 
find a way to keep the fields separate. Place, people and keywords are 
all put into one or more various IPTC or XML fields. This is more a 
problem with the metadata (multiple) standards more than Digikam. 
Sometimes the data is in the form People/Name, People/Name and sometimes 
just Name/Name.  But people  places and keywords are not the same (in 
database terms) and should be kept separate. People are put into 
RegionPersonDisplayName and into RegionName so I could retrieve them.

I shall either have to not export 'tags' or find a routine to unravel 
Place from the string of keywords. I will work on how to create the XMP 
fields Country/City/Location... rather then using the country in 'tags' 
in Digikam. I will get there in the end I hope.

Please let me know if by using filters or anything how to print or 
export this information. I can put together an example of what I am 
aiming for.