I added hierarchical keywords using Metadata Templates this created @keywords categories but the values were not propagated to the universal thesaurus. Short of adding those terms one by one from the keywords panel, is there a way to do it in bulk as there many keywords to be added?
The main feature for adding and managing keywords is the Keyword Panel.
It has an option which automatically adds new keywords you enter to the Thesaurus.
The @Keywords category hierarchy is dynamically created from the actual keywords in your files. It is not the primary feature for adding keywords to files.
Setting metadata via a Metadata Template does not update the thesaurus. MD Templates have no knowledge of the thesaurus or care what kind of metadata you add or manipulate. You are basically doing this from the bottom up.
I recommend you add the keywords you apply in the MD Templates once to your thesaurus by hand.
See this Help topic: https://www.photools.com/help/imatch/#thes_basics.htm#a_imp_db
It may do what you want, if you want all of your existing keywords in the Thesaurus.
I just saw how to do it. In the Thesaurus Manager, the last icon has the option to Import from the Database - that did exactly what I needed :)
Very good. Note that the import also imports all the fluff and random keywords your database may contain. A bit of review and grooming may be needed.
But the main feature for working with keywords is the Keyword Panel. It has tons of features to make working with keywords super-efficient. And it allows you to maintain your thesaurus at the same time.