There should be a relationship but there is an indirect one.
In general, for BI what is needed is some kind of indicator or “measure” in data warehousing lingo, which is the answer to certain question, that could be navigated in different ways. Like “average of X”.
Then you have “dimensions” or “sex”, like time. So you can have “average of X in the last year for Males”.
Those dimensions have a dependency to the original data, maybe aggregated and summarized in a certain way, or could be just the raw original data.
IMHO the “original” data is what should be defined by templates.
Then there is another construct that is the “fact”, which is an event or snapshot of a business event, that was captured in all it’s dimensions (time, sex, …) and is used to calculate the “measure”.
So to feed a data warehouse, we need an ETL to transform the original data defined by templates, into the facts with all their dimensions, in order to be able to calculate the output measures.
In general I wouldn’t represent the facts or the dimensions directly with templates. Maybe there could be some cases where the original data is very similar to the fact tables, but this is not always the case.
What I see as an advantage, which is a very difficult step to start with in BI projects, is with openEHR all the clinical data sources are standardized. Sanitation and standardization of the sources is a required step for any ETL, and openEHR simplifies that a lot having all the data defined by templates.
But there is a missing link, which I think in a certain way is covered by the FHIR mapping language, is to have some formal way to express mappings from openEHR to custom data models and from custom data models to openEHR, which will also cover part of the gap for any ETL, for BI or for simple data migration from legacy to openEHR repos, or between openEHR repos to custom databases like research ones.
Maybe other guys can explain this better, my memory is a littler rusty in terms of BI concepts, but I have the basics.
All this is also why I told @Jelte that specific requirements should be specified before looking for tools, since the ETL is a required but currently custom step for BI.