Hi Djdk,
I think creating a new delta publisher micro service providing/republishing a specialised/filtered stream (should we call it a derivative stream? 
) with only the fields you are interested in might be an interesting option to explore further.
With regards to the topic space, to maximise and make the best of Solace’s filtering capabilities via topic wildcards, you are facing the challenge of trying to compress a multi dimensional map into a single dimensional topic space.
One way to approach this could be to break each row into a root topic followed by the column values (or an indicator for a changed value keeping the actual value in the payload of the message), like:
row1/columnA/columnB/columnC/…
row2/columnA/columnB/columnC/…
…
And so on. Not sure how big your two dimensional maps are, so this might get challenging, if they are very large.
Keep in mind that the max length for Solace topics is 250 bytes when designing your topic taxonomy.
Best regards,
Christian