Interoperability of old eMRs and new ones is a nightmare.
It's less complex if it's system A -> B, but here we have systems A-K all going to System L.
Data extraction in the former situation is a fairly straightforward process, but where you have a person who has data across multiple systems (having received care in multiple LHDs over the course of their life), you have a data nightmare.
Therein lies an opportunity for a good bridging option, and my opinion is that EPICs built in data extraction tools are not going to cut the mustard for the latter situation. It was barely passable for the former situation in ACT. Opinion based on my user experience as I work across both health systems.