Regarding the issue with FTS5 returning no results - have you populated your FTS5 table with the data? (https://stackoverflow.com/a/69981377/11190073)

where xxx like '%yyy%' - no index and no embedded full-text search solutions of RDBMS(at least from my experience with MySQL and MariaDB fulltext solutions) yields better performance results, than search engines like Lucene/ElasticSearch/... Of course it hugely depends on data cardinality and your DB configuration - if your orders table is in hundreds/thousands/tensOfThousands, where o.note like '%COOP%' might perform just OK since your DB will probably cache all your data in memory, but if you're talking about hundredsOfThousands/millions and beyond, don't even consider where clause with like operand