Is the ingest converter tool (https://www.elastic.co/guide/en/logstash/current/ingest-converter.html) still maintained? I saw that based on github it was last updated 2 years ago.
Currently it is lacking a lot of processors like kv, remove_field, etc and also support for painless scripts is missing.
On the other hand it is very buggy (try for example to convert kafka ingest pipeline -https://github.com/elastic/beats/blob/master/filebeat/module/kafka/log/ingest/pipeline.json).
I've found an opened github issue, https://github.com/elastic/beats/issues/6280, which address somehow the same problem of converting ingest pipelines in logstash dsl.