Welcome to the community! I’m highly interested in your work.
I myself am working at a vendor on adding structured data from free text using ML at input time. For some related discussion see Semi structured narrative data
Learning openEHR is not easy, and it’s proven hard to produce easy “getting started” materials. Because there’s a lot of different backgrounds (clinical, informatics, policymakers) and levels of understanding of health informatics, and due to the complexity of healthcare data openEHR is highly complex as well. And depending on your experience some basics of openEHR can be counterintuitive.
If you search this forum or openEHR.org or YouTube some good material will come up.
And please don’t hesitate to ask for more help or to test your assumptions and understanding, people are very much willing to help here.
The highmed project from Germany may be interesting to you as well, afaik it’s not doing (much) ML, but it is transforming data into openEHR for (currently) research purposes. Ping @birger.haarbrandt