I have never seen in professional literature the following data but it must be noted.
The world of currencies undergo a considerable change in about ever 10 year.
Monetary systems of the world collapsed quite many times in the last hundred years. This required setting up new monetary systems.
Also originally certain currencies like USD was tied to Gold. This is not the case, anymore.
Let's take this as an example.
A USA dollar required a Gold reserve. Is not the same as a USA dollar that can be freely printed. I would go as far as saying, "it is a different currency". It is still cold USA dollar but it is a new currency.
Similar can be said about other currencies like CHF, HUF, EUR, etc.
Forex traders tend to use fundamental analyses on long-term investments. And yes, it is true that technical analyses results "seem to be checking out correctly" but still I would not try to relay on it.
EUR is only 5-year-old
So what? I understand that some traders try to get long-term historical EUR data buy comparing it to ECU or before that to Deutche mark. It is like comparing oranges to apples. EUR has a very far-fetched resemblance to the old Deutche mark: different world structure, different countries, different money system, different trades between countries.