It would be helpful, if you could post the share your result link from after the test, here is an example:
https://www.waveform.com/tools/bufferbloat?test-id=8670bf71-99c1-4f52-9eec-fe8a42b5c22d
So SQM’s AQMs all use a 5ms delay target and the observation is that under load you can expect roughly two times the target as delay empirically and theoretocally >= one time target, so with its default configuration (which is suitable for use over the wider internet) will not give you much better than what you saw.
Download shaping is a bit approximate (since it typically happens on the wrong side of the bottleneck, there is always the chance that too many packets rush in at a given time interval, such that they queue up in the under-managed and over-sized upstream buffers, resulting in increased bufferbloat). That said, for bidirectionally saturating traffic the omnia tops out at around 500/500 Mbps (and only after adding option packet_steering '1' to the global options in /etc/config/network).
So you could try the latter, but I guess you will still end with >= ~ 5ms delay, unless you set a lower target/interval (how to do this depends on which AQM you use, cake or HTB+fq_codel).