I have tried this approach to get case-insensitive tag-bases search suggestions and it didn’t work.
Error from the log:
"Multiple values encountered for non multiValued copy field
property.XWiki.TagClass.tags_sortString"
I have then tried jmiba’s approach from this thread and found that to work.
He proposes adding a new field “tag”, declaring it “multivalue”=“true” and then copying to that.
One can then add search suggestions based on this new field and voila, it works!