I am porting some content to D8 from a SharePoint site via CSVs. However, the taxonomies and users were migrated manually, which means I cannot us the Migrate plugin to lookup the ids from the term name. For short taxonomies, I have successfully used the map plugin, but this is a serious challenge for taxonomies with lots of terms. So far my migration is all config (yml) with no callbacks or other php.
Is there a way to handle this in the yml?
If not could it be easily handled with the callback plugin?
Any help will be appreciated.