The ATSB report doesn't state what the lateral separation was. It looks like it would have been close (one aircraft at 4nm final, one turning base at 3.5 NM to run).
Was there a difference in cleared altitude to ensure separation?
It looks like the problem was that both aircraft were cleared for the same altitude (block), and crossed paths without any assurance of lateral separation.
Just because they didn't come close doesn't mean it was safe. It appears that part of the reason they weren't closer was the ATC misunderstanding.
ATC also instructed "minimum speed" to the aircraft on final - is there any leeway to vary speed on final at <4NM?
According to one report Airservices risk management assessed the likelihood of simultaneous go arounds as 1 in 175 years for LAHSO, but it has happened twice in 5 years?
It doesn't sound like things were working as designed.
60 seconds time difference at Überlingen and people would be saying that there was no issue, the aircraft never came close to each other.