The Estonian national standards organization and the standards themselves are totally legitimate. I don’t see any reason why you would have a problem with them with an auditor.
And a multi-user license allows you to download a PDF that can be opened by anyone that can access the file. The terms of service say it can be used by up to X number of users simultaneously. To my knowledge, this is enforced via the honor system, and not any technical system.
Here is what the National foreword says:
This is telling you that the Estonian standard is just the English version of the European standard.
Then the European forward says
This tells you that the European version is the same as the International.
I will say things can be a bit confusing at times if the dates (years) of a European Standard and its International equivalent do not align. For example EN 60601-1 says 2006, while IEC 60601-1 says 2005. But the body of the standard is identical.
And sometimes the EU will add annexes or Amendments that aren’t in the International standard (ex: Annexes ZZA and ZZB, which describe how the standard relates to European regulations). But these can be easily explained/understood.