Invalid testing proceedure?
Ity seems to me that it could be argued that the testing procedure used was invalid, at least for windscreens.
According the the report, the objects were launched towards a stationary windscreen, whereas in actual flight the effect is much more a case of the windscreen being launched towards a relatively stationary object. Presumably some minor effort is put into designing modern airliners so that they have a smooth airflow around them, which I would expect to lift something as light as a hobby grade drone well away from the windscreen before it had a chance to impact it. If you've ever traveled in the rain, in an open top sports car at any reasonable speed, then you've seen this principle at work -yes, the drones are heavier that raindrops, but then the air velocity is much higher as well.
This would not prevent engine ingestion of a drone however - the business of a jet engine is to suck in as much air as possible, including anything that might be floating in it.